Java 11 migrate remaining p (#1122)

* Moves partial-response to Java 11

* Moves pipeline to Java 11

* Moves poison-pill to Java 11

* Moves priority-queue to Java 11

* Moves private-class-data to Java 11

* Moves producer-consumer to Java 11

* Moves promise to Java 11

* Moves property to Java 11

* Moves prototype to Java 11

* Moves proxy to Java 11

* Corrects checkstyle errors

* Fixes build for pipeline pattern

master-worker-pattern/src/main/java/com/iluwatar/masterworker/App.java

@@ -24,6 +24,11 @@
 package com.iluwatar.masterworker;
 
 import com.iluwatar.masterworker.system.ArrayTransposeMasterWorker;
+import com.iluwatar.masterworker.system.MasterWorker;
+import com.iluwatar.masterworker.system.systemmaster.ArrayTransposeMaster;
+import com.iluwatar.masterworker.system.systemmaster.Master;
+import com.iluwatar.masterworker.system.systemworkers.ArrayTransposeWorker;
+import com.iluwatar.masterworker.system.systemworkers.Worker;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 

page-object/pom.xml

@@ -26,6 +26,23 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
+    <properties>
+        <maven.compiler.source>11</maven.compiler.source>
+        <maven.compiler.target>11</maven.compiler.target>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>net.sourceforge.htmlunit</groupId>
+            <artifactId>htmlunit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>RELEASE</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>

page-object/sample-application/src/main/java/com/iluwatar/pageobject/App.java

@@ -71,8 +71,8 @@ public final class App {
   public static void main(String[] args) {
 
     try {
-      File applicationFile =
+      var classLoader = App.class.getClassLoader();
-          new File(App.class.getClassLoader().getResource("sample-ui/login.html").getPath());
+      var applicationFile = new File(classLoader.getResource("sample-ui/login.html").getPath());
 
       // should work for unix like OS (mac, unix etc...)
       if (Desktop.isDesktopSupported()) {

page-object/src/main/java/com/iluwatar/pageobject/App.java

@@ -67,8 +67,8 @@ public final class App {
   public static void main(String[] args) {
 
     try {
-      File applicationFile =
+      var classLoader = App.class.getClassLoader();
-          new File(App.class.getClassLoader().getResource("sample-ui/login.html").getPath());
+      var applicationFile = new File(classLoader.getResource("sample-ui/login.html").getPath());
 
       // Should work for unix like OS (mac, unix etc...)
       if (Desktop.isDesktopSupported()) {

page-object/src/test/java/com/iluwatar/pageobject/AlbumListPageTest.java

@@ -23,14 +23,14 @@
 
 package com.iluwatar.pageobject;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import com.gargoylesoftware.htmlunit.WebClient;
 import com.iluwatar.pageobject.pages.AlbumListPage;
 import com.iluwatar.pageobject.pages.AlbumPage;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 /**
  * Test Album Selection and Album Listing
  */
@@ -45,7 +45,7 @@ public class AlbumListPageTest {
 
   @Test
   public void testSelectAlbum() {
-    AlbumPage albumPage = albumListPage.selectAlbum("21");
+    var albumPage = albumListPage.selectAlbum("21");
     albumPage.navigateToPage();
     assertTrue(albumPage.isAt());
   }

page-object/src/test/java/com/iluwatar/pageobject/AlbumPageTest.java

@@ -23,14 +23,14 @@
 
 package com.iluwatar.pageobject;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import com.gargoylesoftware.htmlunit.WebClient;
 import com.iluwatar.pageobject.pages.AlbumListPage;
 import com.iluwatar.pageobject.pages.AlbumPage;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 /**
  * Test Album Page Operations
  */
@@ -46,7 +46,7 @@ public class AlbumPageTest {
   @Test
   public void testSaveAlbum() {
 
-    AlbumPage albumPageAfterChanges = albumPage
+    var albumPageAfterChanges = albumPage
         .changeAlbumTitle("25")
         .changeArtist("Adele Laurie Blue Adkins")
         .changeAlbumYear(2015)
@@ -60,7 +60,7 @@ public class AlbumPageTest {
 
   @Test
   public void testCancelChanges() {
-    AlbumListPage albumListPage = albumPage.cancelChanges();
+    var albumListPage = albumPage.cancelChanges();
     albumListPage.navigateToPage();
     assertTrue(albumListPage.isAt());
   }

page-object/src/test/java/com/iluwatar/pageobject/LoginPageTest.java

@@ -23,14 +23,14 @@
 
 package com.iluwatar.pageobject;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import com.gargoylesoftware.htmlunit.WebClient;
 import com.iluwatar.pageobject.pages.AlbumListPage;
 import com.iluwatar.pageobject.pages.LoginPage;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 /**
  * Test Login Page Object
  */
@@ -45,7 +45,7 @@ public class LoginPageTest {
 
   @Test
   public void testLogin() {
-    AlbumListPage albumListPage = loginPage
+    var albumListPage = loginPage
         .enterUsername("admin")
         .enterPassword("password")
         .login();

page-object/src/test/java/com/iluwatar/pageobject/pages/AlbumListPage.java

@@ -26,7 +26,6 @@ package com.iluwatar.pageobject.pages;
 import com.gargoylesoftware.htmlunit.WebClient;
 import com.gargoylesoftware.htmlunit.html.HtmlAnchor;
 import com.gargoylesoftware.htmlunit.html.HtmlPage;
-
 import java.io.IOException;
 import java.util.List;
 
@@ -79,8 +78,8 @@ public class AlbumListPage extends Page {
    */
   public AlbumPage selectAlbum(String albumTitle) {
     // uses XPath to find list of html anchor tags with the class album in it
-    List<HtmlAnchor> albumLinks = (List<HtmlAnchor>) page.getByXPath("//tr[@class='album']//a");
+    var albumLinks = (List<HtmlAnchor>) page.getByXPath("//tr[@class='album']//a");
-    for (HtmlAnchor anchor : albumLinks) {
+    for (var anchor : albumLinks) {
       if (anchor.getTextContent().equals(albumTitle)) {
         try {
           anchor.click();

page-object/src/test/java/com/iluwatar/pageobject/pages/AlbumPage.java

@@ -30,7 +30,6 @@ import com.gargoylesoftware.htmlunit.html.HtmlPage;
 import com.gargoylesoftware.htmlunit.html.HtmlSelect;
 import com.gargoylesoftware.htmlunit.html.HtmlSubmitInput;
 import com.gargoylesoftware.htmlunit.html.HtmlTextInput;
-
 import java.io.IOException;
 
 /**
@@ -83,7 +82,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeAlbumTitle(String albumTitle) {
-    HtmlTextInput albumTitleInputTextField = (HtmlTextInput) page.getElementById("albumTitle");
+    var albumTitleInputTextField = (HtmlTextInput) page.getElementById("albumTitle");
     albumTitleInputTextField.setText(albumTitle);
     return this;
   }
@@ -96,7 +95,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeArtist(String artist) {
-    HtmlTextInput artistInputTextField = (HtmlTextInput) page.getElementById("albumArtist");
+    var artistInputTextField = (HtmlTextInput) page.getElementById("albumArtist");
     artistInputTextField.setText(artist);
     return this;
   }
@@ -109,8 +108,8 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeAlbumYear(int year) {
-    HtmlSelect albumYearSelectOption = (HtmlSelect) page.getElementById("albumYear");
+    var albumYearSelectOption = (HtmlSelect) page.getElementById("albumYear");
-    HtmlOption yearOption = albumYearSelectOption.getOptionByValue(Integer.toString(year));
+    var yearOption = albumYearSelectOption.getOptionByValue(Integer.toString(year));
     albumYearSelectOption.setSelectedAttribute(yearOption, true);
     return this;
   }
@@ -123,7 +122,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeAlbumRating(String albumRating) {
-    HtmlTextInput albumRatingInputTextField = (HtmlTextInput) page.getElementById("albumRating");
+    var albumRatingInputTextField = (HtmlTextInput) page.getElementById("albumRating");
     albumRatingInputTextField.setText(albumRating);
     return this;
   }
@@ -135,7 +134,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeNumberOfSongs(int numberOfSongs) {
-    HtmlNumberInput numberOfSongsNumberField = (HtmlNumberInput) page.getElementById("numberOfSongs");
+    var numberOfSongsNumberField = (HtmlNumberInput) page.getElementById("numberOfSongs");
     numberOfSongsNumberField.setText(Integer.toString(numberOfSongs));
     return this;
   }
@@ -147,7 +146,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumListPage}
    */
   public AlbumListPage cancelChanges() {
-    HtmlSubmitInput cancelButton = (HtmlSubmitInput) page.getElementById("cancelButton");
+    var cancelButton = (HtmlSubmitInput) page.getElementById("cancelButton");
     try {
       cancelButton.click();
     } catch (IOException e) {
@@ -163,7 +162,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage saveChanges() {
-    HtmlSubmitInput saveButton = (HtmlSubmitInput) page.getElementById("saveButton");
+    var saveButton = (HtmlSubmitInput) page.getElementById("saveButton");
     try {
       saveButton.click();
     } catch (IOException e) {

page-object/src/test/java/com/iluwatar/pageobject/pages/LoginPage.java

@@ -79,7 +79,7 @@ public class LoginPage extends Page {
    * @return {@link LoginPage}
    */
   public LoginPage enterUsername(String username) {
-    HtmlTextInput usernameInputTextField = (HtmlTextInput) page.getElementById("username");
+    var usernameInputTextField = (HtmlTextInput) page.getElementById("username");
     usernameInputTextField.setText(username);
     return this;
   }
@@ -92,7 +92,7 @@ public class LoginPage extends Page {
    * @return {@link LoginPage}
    */
   public LoginPage enterPassword(String password) {
-    HtmlPasswordInput passwordInputPasswordField = (HtmlPasswordInput) page.getElementById("password");
+    var passwordInputPasswordField = (HtmlPasswordInput) page.getElementById("password");
     passwordInputPasswordField.setText(password);
     return this;
   }
@@ -101,11 +101,11 @@ public class LoginPage extends Page {
   /**
    * Clicking on the login button to 'login'
    *
-   * @return {@link AlbumListPage}
+   * @return {@link AlbumListPage} - this is the page that user gets navigated to once successfully
-   *        - this is the page that user gets navigated to once successfully logged in
+   *     logged in
    */
   public AlbumListPage login() {
-    HtmlSubmitInput loginButton = (HtmlSubmitInput) page.getElementById("loginButton");
+    var loginButton = (HtmlSubmitInput) page.getElementById("loginButton");
     try {
       loginButton.click();
     } catch (IOException e) {

page-object/src/test/java/com/iluwatar/pageobject/pages/Page.java

@@ -31,8 +31,7 @@ import com.gargoylesoftware.htmlunit.WebClient;
 public abstract class Page {
 
   /**
-   * Application Under Test path
+   * Application Under Test path This directory location is where html web pages are located
-   * This directory location is where html web pages are located
    */
   public static final String AUT_PATH = "src/main/resources/sample-ui/";
 

page-object/test-automation/src/main/java/com/iluwatar/pageobject/AlbumListPage.java

@@ -81,8 +81,8 @@ public class AlbumListPage extends Page {
    */
   public AlbumPage selectAlbum(String albumTitle) {
     // uses XPath to find list of html anchor tags with the class album in it
-    List<HtmlAnchor> albumLinks = (List<HtmlAnchor>) page.getByXPath("//tr[@class='album']//a");
+    var albumLinks = (List<HtmlAnchor>) page.getByXPath("//tr[@class='album']//a");
-    for (HtmlAnchor anchor : albumLinks) {
+    for (var anchor : albumLinks) {
       if (anchor.getTextContent().equals(albumTitle)) {
         try {
           anchor.click();

page-object/test-automation/src/main/java/com/iluwatar/pageobject/AlbumPage.java

@@ -25,7 +25,6 @@ package com.iluwatar.pageobject;
 
 import com.gargoylesoftware.htmlunit.WebClient;
 import com.gargoylesoftware.htmlunit.html.HtmlNumberInput;
-import com.gargoylesoftware.htmlunit.html.HtmlOption;
 import com.gargoylesoftware.htmlunit.html.HtmlPage;
 import com.gargoylesoftware.htmlunit.html.HtmlSelect;
 import com.gargoylesoftware.htmlunit.html.HtmlSubmitInput;
@@ -85,7 +84,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeAlbumTitle(String albumTitle) {
-    HtmlTextInput albumTitleInputTextField = (HtmlTextInput) page.getElementById("albumTitle");
+    var albumTitleInputTextField = (HtmlTextInput) page.getElementById("albumTitle");
     albumTitleInputTextField.setText(albumTitle);
     return this;
   }
@@ -98,7 +97,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeArtist(String artist) {
-    HtmlTextInput artistInputTextField = (HtmlTextInput) page.getElementById("albumArtist");
+    var artistInputTextField = (HtmlTextInput) page.getElementById("albumArtist");
     artistInputTextField.setText(artist);
     return this;
   }
@@ -111,8 +110,8 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeAlbumYear(int year) {
-    HtmlSelect albumYearSelectOption = (HtmlSelect) page.getElementById("albumYear");
+    var albumYearSelectOption = (HtmlSelect) page.getElementById("albumYear");
-    HtmlOption yearOption = albumYearSelectOption.getOptionByValue(Integer.toString(year));
+    var yearOption = albumYearSelectOption.getOptionByValue(Integer.toString(year));
     albumYearSelectOption.setSelectedAttribute(yearOption, true);
     return this;
   }
@@ -125,7 +124,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeAlbumRating(String albumRating) {
-    HtmlTextInput albumRatingInputTextField = (HtmlTextInput) page.getElementById("albumRating");
+    var albumRatingInputTextField = (HtmlTextInput) page.getElementById("albumRating");
     albumRatingInputTextField.setText(albumRating);
     return this;
   }
@@ -137,8 +136,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage changeNumberOfSongs(int numberOfSongs) {
-    HtmlNumberInput numberOfSongsNumberField =
+    var numberOfSongsNumberField = (HtmlNumberInput) page.getElementById("numberOfSongs");
-        (HtmlNumberInput) page.getElementById("numberOfSongs");
     numberOfSongsNumberField.setText(Integer.toString(numberOfSongs));
     return this;
   }
@@ -150,7 +148,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumListPage}
    */
   public AlbumListPage cancelChanges() {
-    HtmlSubmitInput cancelButton = (HtmlSubmitInput) page.getElementById("cancelButton");
+    var cancelButton = (HtmlSubmitInput) page.getElementById("cancelButton");
     try {
       cancelButton.click();
     } catch (IOException e) {
@@ -166,7 +164,7 @@ public class AlbumPage extends Page {
    * @return {@link AlbumPage}
    */
   public AlbumPage saveChanges() {
-    HtmlSubmitInput saveButton = (HtmlSubmitInput) page.getElementById("saveButton");
+    var saveButton = (HtmlSubmitInput) page.getElementById("saveButton");
     try {
       saveButton.click();
     } catch (IOException e) {

page-object/test-automation/src/main/java/com/iluwatar/pageobject/LoginPage.java

@@ -82,7 +82,7 @@ public class LoginPage extends Page {
    * @return {@link LoginPage}
    */
   public LoginPage enterUsername(String username) {
-    HtmlTextInput usernameInputTextField = (HtmlTextInput) page.getElementById("username");
+    var usernameInputTextField = (HtmlTextInput) page.getElementById("username");
     usernameInputTextField.setText(username);
     return this;
   }
@@ -95,8 +95,7 @@ public class LoginPage extends Page {
    * @return {@link LoginPage}
    */
   public LoginPage enterPassword(String password) {
-    HtmlPasswordInput passwordInputPasswordField =
+    var passwordInputPasswordField = (HtmlPasswordInput) page.getElementById("password");
-        (HtmlPasswordInput) page.getElementById("password");
     passwordInputPasswordField.setText(password);
     return this;
   }
@@ -109,7 +108,7 @@ public class LoginPage extends Page {
    *     logged in
    */
   public AlbumListPage login() {
-    HtmlSubmitInput loginButton = (HtmlSubmitInput) page.getElementById("loginButton");
+    var loginButton = (HtmlSubmitInput) page.getElementById("loginButton");
     try {
       loginButton.click();
     } catch (IOException e) {

page-object/test-automation/src/test/java/com/iluwatar/pageobject/AlbumListPageTest.java

@@ -23,14 +23,12 @@
 
 package com.iluwatar.pageobject;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import com.gargoylesoftware.htmlunit.WebClient;
-import com.iluwatar.pageobject.AlbumListPage;
-import com.iluwatar.pageobject.AlbumPage;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 /**
  * Test Album Selection and Album Listing
  */
@@ -45,7 +43,7 @@ public class AlbumListPageTest {
 
   @Test
   public void testSelectAlbum() {
-    AlbumPage albumPage = albumListPage.selectAlbum("21");
+    var albumPage = albumListPage.selectAlbum("21");
     albumPage.navigateToPage();
     assertTrue(albumPage.isAt());
   }

page-object/test-automation/src/test/java/com/iluwatar/pageobject/AlbumPageTest.java

@@ -25,11 +25,10 @@ package com.iluwatar.pageobject;
 
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import com.gargoylesoftware.htmlunit.WebClient;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import com.gargoylesoftware.htmlunit.WebClient;
-
 /**
  * Test Album Page Operations
  */
@@ -45,7 +44,7 @@ public class AlbumPageTest {
   @Test
   public void testSaveAlbum() {
 
-    AlbumPage albumPageAfterChanges = albumPage
+    var albumPageAfterChanges = albumPage
         .changeAlbumTitle("25")
         .changeArtist("Adele Laurie Blue Adkins")
         .changeAlbumYear(2015)
@@ -59,7 +58,7 @@ public class AlbumPageTest {
 
   @Test
   public void testCancelChanges() {
-    AlbumListPage albumListPage = albumPage.cancelChanges();
+    var albumListPage = albumPage.cancelChanges();
     albumListPage.navigateToPage();
     assertTrue(albumListPage.isAt());
   }

page-object/test-automation/src/test/java/com/iluwatar/pageobject/LoginPageTest.java

@@ -25,11 +25,10 @@ package com.iluwatar.pageobject;
 
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import com.gargoylesoftware.htmlunit.WebClient;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import com.gargoylesoftware.htmlunit.WebClient;
-
 /**
  * Test Login Page Object
  */
@@ -44,7 +43,7 @@ public class LoginPageTest {
 
   @Test
   public void testLogin() {
-    AlbumListPage albumListPage = loginPage
+    var albumListPage = loginPage
         .enterUsername("admin")
         .enterPassword("password")
         .login();

partial-response/src/main/java/com/iluwatar/partialresponse/App.java

@@ -44,30 +44,31 @@ public class App {
    * @param args program argument.
    */
   public static void main(String[] args) throws Exception {
-    Map<Integer, Video> videos = Map.of(
+    var videos = Map.of(
         1, new Video(1, "Avatar", 178, "epic science fiction film",
             "James Cameron", "English"),
         2, new Video(2, "Godzilla Resurgence", 120, "Action & drama movie|",
             "Hideaki Anno", "Japanese"),
         3, new Video(3, "Interstellar", 169, "Adventure & Sci-Fi",
-            "Christopher Nolan", "English"));
+            "Christopher Nolan", "English")
-    VideoResource videoResource = new VideoResource(new FieldJsonMapper(), videos);
+    );
+    var videoResource = new VideoResource(new FieldJsonMapper(), videos);
 
 
     LOGGER.info("Retrieving full response from server:-");
     LOGGER.info("Get all video information:");
-    String videoDetails = videoResource.getDetails(1);
+    var videoDetails = videoResource.getDetails(1);
     LOGGER.info(videoDetails);
 
     LOGGER.info("----------------------------------------------------------");
 
     LOGGER.info("Retrieving partial response from server:-");
     LOGGER.info("Get video @id, @title, @director:");
-    String specificFieldsDetails = videoResource.getDetails(3, "id", "title", "director");
+    var specificFieldsDetails = videoResource.getDetails(3, "id", "title", "director");
     LOGGER.info(specificFieldsDetails);
 
     LOGGER.info("Get video @id, @length:");
-    String videoLength = videoResource.getDetails(3, "id", "length");
+    var videoLength = videoResource.getDetails(3, "id", "length");
     LOGGER.info(videoLength);
   }
 }

partial-response/src/main/java/com/iluwatar/partialresponse/FieldJsonMapper.java

@@ -38,13 +38,16 @@ public class FieldJsonMapper {
    * @return json of required fields from video
    */
   public String toJson(Video video, String[] fields) throws Exception {
-    StringBuilder json = new StringBuilder().append("{");
+    var json = new StringBuilder().append("{");
 
-    for (int i = 0, fieldsLength = fields.length; i < fieldsLength; i++) {
+    var i = 0;
+    var fieldsLength = fields.length;
+    while (i < fieldsLength) {
       json.append(getString(video, Video.class.getDeclaredField(fields[i])));
       if (i != fieldsLength - 1) {
         json.append(",");
       }
+      i++;
     }
     json.append("}");
     return json.toString();
@@ -52,7 +55,7 @@ public class FieldJsonMapper {
 
   private String getString(Video video, Field declaredField) throws IllegalAccessException {
     declaredField.setAccessible(true);
-    Object value = declaredField.get(video);
+    var value = declaredField.get(video);
     if (declaredField.get(video) instanceof Integer) {
       return "\"" + declaredField.getName() + "\"" + ": " + value;
     }

partial-response/src/test/java/com/iluwatar/partialresponse/AppTest.java

@@ -32,8 +32,7 @@ public class AppTest {
 
   @Test
   public void main() throws Exception {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 
 }

partial-response/src/test/java/com/iluwatar/partialresponse/FieldJsonMapperTest.java

@@ -23,11 +23,11 @@
 
 package com.iluwatar.partialresponse;
 
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Before;
 import org.junit.Test;
 
-import static org.junit.Assert.assertEquals;
-
 /**
  * tests {@link FieldJsonMapper}.
  */
@@ -41,12 +41,15 @@ public class FieldJsonMapperTest {
 
   @Test
   public void shouldReturnJsonForSpecifiedFieldsInVideo() throws Exception {
-    String[] fields = new String[]{"id", "title", "length"};
+    var fields = new String[]{"id", "title", "length"};
-    Video video = new Video(2, "Godzilla Resurgence", 120, "Action & drama movie|", "Hideaki Anno", "Japanese");
+    var video = new Video(
+        2, "Godzilla Resurgence", 120,
+        "Action & drama movie|", "Hideaki Anno", "Japanese"
+    );
 
-    String jsonFieldResponse = mapper.toJson(video, fields);
+    var jsonFieldResponse = mapper.toJson(video, fields);
 
-    String expectedDetails = "{\"id\": 2,\"title\": \"Godzilla Resurgence\",\"length\": 120}";
+    var expectedDetails = "{\"id\": 2,\"title\": \"Godzilla Resurgence\",\"length\": 120}";
     assertEquals(expectedDetails, jsonFieldResponse);
   }
 }

partial-response/src/test/java/com/iluwatar/partialresponse/VideoResourceTest.java

@@ -23,19 +23,18 @@
 
 package com.iluwatar.partialresponse;
 
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.when;
+
+import java.util.Map;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 
-import java.util.Map;
-
-import static org.junit.Assert.assertEquals;
-import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.when;
-
 /**
  * tests {@link VideoResource}.
  */
@@ -48,33 +47,33 @@ public class VideoResourceTest {
 
   @Before
   public void setUp() {
-    Map<Integer, Video> videos = Map.of(
+    var videos = Map.of(
-            1, new Video(1, "Avatar", 178, "epic science fiction film",
+        1, new Video(1, "Avatar", 178, "epic science fiction film",
-                    "James Cameron", "English"),
+            "James Cameron", "English"),
-            2, new Video(2, "Godzilla Resurgence", 120, "Action & drama movie|",
+        2, new Video(2, "Godzilla Resurgence", 120, "Action & drama movie|",
-                    "Hideaki Anno", "Japanese"),
+            "Hideaki Anno", "Japanese"),
-            3, new Video(3, "Interstellar", 169, "Adventure & Sci-Fi",
+        3, new Video(3, "Interstellar", 169, "Adventure & Sci-Fi",
-                    "Christopher Nolan", "English"));
+            "Christopher Nolan", "English"));
     resource = new VideoResource(fieldJsonMapper, videos);
   }
 
   @Test
   public void shouldGiveVideoDetailsById() throws Exception {
-    String actualDetails = resource.getDetails(1);
+    var actualDetails = resource.getDetails(1);
 
-    String expectedDetails = "{\"id\": 1,\"title\": \"Avatar\",\"length\": 178,\"description\": "
+    var expectedDetails = "{\"id\": 1,\"title\": \"Avatar\",\"length\": 178,\"description\": "
         + "\"epic science fiction film\",\"director\": \"James Cameron\",\"language\": \"English\",}";
     assertEquals(expectedDetails, actualDetails);
   }
 
   @Test
   public void shouldGiveSpecifiedFieldsInformationOfVideo() throws Exception {
-    String[] fields = new String[]{"id", "title", "length"};
+    var fields = new String[]{"id", "title", "length"};
 
-    String expectedDetails = "{\"id\": 1,\"title\": \"Avatar\",\"length\": 178}";
+    var expectedDetails = "{\"id\": 1,\"title\": \"Avatar\",\"length\": 178}";
     when(fieldJsonMapper.toJson(any(Video.class), eq(fields))).thenReturn(expectedDetails);
 
-    String actualFieldsDetails = resource.getDetails(2, fields);
+    var actualFieldsDetails = resource.getDetails(2, fields);
 
     assertEquals(expectedDetails, actualFieldsDetails);
   }

pipeline/src/main/java/com/iluwatar/pipeline/ConvertToCharArrayHandler.java

@@ -36,11 +36,12 @@ class ConvertToCharArrayHandler implements Handler<String, char[]> {
 
   @Override
   public char[] process(String input) {
-    char[] characters = input.toCharArray();
+    var characters = input.toCharArray();
-    LOGGER
+    var string = Arrays.toString(characters);
-        .info(String.format("Current handler: %s, input is %s of type %s, output is %s, of type %s",
+    LOGGER.info(
-            ConvertToCharArrayHandler.class, input, String.class, Arrays
+        String.format("Current handler: %s, input is %s of type %s, output is %s, of type %s",
-                .toString(characters), Character[].class));
+            ConvertToCharArrayHandler.class, input, String.class, string, Character[].class)
+    );
 
     return characters;
   }

pipeline/src/main/java/com/iluwatar/pipeline/RemoveAlphabetsHandler.java

@@ -23,6 +23,7 @@
 
 package com.iluwatar.pipeline;
 
+import java.util.function.IntPredicate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -36,18 +37,14 @@ class RemoveAlphabetsHandler implements Handler<String, String> {
 
   @Override
   public String process(String input) {
-    StringBuilder inputWithoutAlphabets = new StringBuilder();
+    var inputWithoutAlphabets = new StringBuilder();
+    var isAlphabetic = (IntPredicate) Character::isAlphabetic;
+    input.chars()
+        .filter(isAlphabetic.negate())
+        .mapToObj(x -> (char) x)
+        .forEachOrdered(inputWithoutAlphabets::append);
 
-    for (int index = 0; index < input.length(); index++) {
+    var inputWithoutAlphabetsStr = inputWithoutAlphabets.toString();
-      char currentCharacter = input.charAt(index);
-      if (Character.isAlphabetic(currentCharacter)) {
-        continue;
-      }
-
-      inputWithoutAlphabets.append(currentCharacter);
-    }
-
-    String inputWithoutAlphabetsStr = inputWithoutAlphabets.toString();
     LOGGER.info(
         String.format(
             "Current handler: %s, input is %s of type %s, output is %s, of type %s",

pipeline/src/main/java/com/iluwatar/pipeline/RemoveDigitsHandler.java

@@ -23,6 +23,7 @@
 
 package com.iluwatar.pipeline;
 
+import java.util.function.IntPredicate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -36,21 +37,20 @@ class RemoveDigitsHandler implements Handler<String, String> {
 
   @Override
   public String process(String input) {
-    StringBuilder inputWithoutDigits = new StringBuilder();
+    var inputWithoutDigits = new StringBuilder();
+    var isDigit = (IntPredicate) Character::isDigit;
+    input.chars()
+        .filter(isDigit.negate())
+        .mapToObj(x -> (char) x)
+        .forEachOrdered(inputWithoutDigits::append);
 
-    for (int index = 0; index < input.length(); index++) {
+    var inputWithoutDigitsStr = inputWithoutDigits.toString();
-      char currentCharacter = input.charAt(index);
+    LOGGER.info(
-      if (Character.isDigit(currentCharacter)) {
+        String.format(
-        continue;
+            "Current handler: %s, input is %s of type %s, output is %s, of type %s",
-      }
+            RemoveDigitsHandler.class, input, String.class, inputWithoutDigitsStr, String.class
-
+        )
-      inputWithoutDigits.append(currentCharacter);
+    );
-    }
-
-    String inputWithoutDigitsStr = inputWithoutDigits.toString();
-    LOGGER
-        .info(String.format("Current handler: %s, input is %s of type %s, output is %s, of type %s",
-            RemoveDigitsHandler.class, input, String.class, inputWithoutDigitsStr, String.class));
 
     return inputWithoutDigitsStr;
   }

pipeline/src/test/java/com/iluwatar/pipeline/AppTest.java

@@ -32,7 +32,6 @@ public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

pipeline/src/test/java/com/iluwatar/pipeline/PipelineTest.java

@@ -23,10 +23,10 @@
 
 package com.iluwatar.pipeline;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Test for {@link Pipeline}
  */
@@ -34,12 +34,12 @@ public class PipelineTest {
 
   @Test
   public void testAddHandlersToPipeline() {
-    Pipeline<String, char[]> filters = new Pipeline<>(new RemoveAlphabetsHandler())
+    var filters = new Pipeline<>(new RemoveAlphabetsHandler())
         .addHandler(new RemoveDigitsHandler())
         .addHandler(new ConvertToCharArrayHandler());
 
     assertArrayEquals(
-        new char[] {'#', '!', '(', '&', '%', '#', '!'},
+        new char[]{'#', '!', '(', '&', '%', '#', '!'},
         filters.execute("#H!E(L&L0O%THE3R#34E!")
     );
   }

poison-pill/src/main/java/com/iluwatar/poison/pill/App.java

@@ -42,26 +42,18 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
-    MessageQueue queue = new SimpleMessageQueue(10000);
+    var queue = new SimpleMessageQueue(10000);
 
-    final Producer producer = new Producer("PRODUCER_1", queue);
+    final var producer = new Producer("PRODUCER_1", queue);
-    final Consumer consumer = new Consumer("CONSUMER_1", queue);
+    final var consumer = new Consumer("CONSUMER_1", queue);
 
-    new Thread() {
+    new Thread(consumer::consume).start();
-      @Override
-      public void run() {
-        consumer.consume();
-      }
-    }.start();
 
-    new Thread() {
+    new Thread(() -> {
-      @Override
+      producer.send("hand shake");
-      public void run() {
+      producer.send("some very important information");
-        producer.send("hand shake");
+      producer.send("bye!");
-        producer.send("some very important information");
+      producer.stop();
-        producer.send("bye!");
+    }).start();
-        producer.stop();
-      }
-    }.start();
   }
 }

poison-pill/src/main/java/com/iluwatar/poison/pill/Consumer.java

@@ -47,22 +47,20 @@ public class Consumer {
    */
   public void consume() {
     while (true) {
-      Message msg;
       try {
-        msg = queue.take();
+        var msg = queue.take();
         if (Message.POISON_PILL.equals(msg)) {
           LOGGER.info("Consumer {} receive request to terminate.", name);
           break;
         }
+        var sender = msg.getHeader(Headers.SENDER);
+        var body = msg.getBody();
+        LOGGER.info("Message [{}] from [{}] received by [{}]", body, sender, name);
       } catch (InterruptedException e) {
         // allow thread to exit
         LOGGER.error("Exception caught.", e);
         return;
       }
-
-      String sender = msg.getHeader(Headers.SENDER);
-      String body = msg.getBody();
-      LOGGER.info("Message [{}] from [{}] received by [{}]", body, sender, name);
     }
   }
 }

poison-pill/src/main/java/com/iluwatar/poison/pill/Producer.java

@@ -57,7 +57,7 @@ public class Producer {
       throw new IllegalStateException(String.format(
           "Producer %s was stopped and fail to deliver requested message [%s].", body, name));
     }
-    Message msg = new SimpleMessage();
+    var msg = new SimpleMessage();
     msg.addHeader(Headers.DATE, new Date().toString());
     msg.addHeader(Headers.SENDER, name);
     msg.setBody(body);

poison-pill/src/test/java/com/iluwatar/poison/pill/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.poison.pill;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

poison-pill/src/test/java/com/iluwatar/poison/pill/ConsumerTest.java

@@ -23,20 +23,19 @@
 
 package com.iluwatar.poison.pill;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.AppenderBase;
+import java.time.LocalDateTime;
+import java.util.LinkedList;
+import java.util.List;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.slf4j.LoggerFactory;
 
-import java.time.LocalDateTime;
-import java.util.LinkedList;
-import java.util.List;
-
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 /**
  * Date: 12/27/15 - 9:45 PM
  *
@@ -58,15 +57,15 @@ public class ConsumerTest {
 
   @Test
   public void testConsume() throws Exception {
-    final Message[] messages = new Message[]{
+    final var messages = List.of(
         createMessage("you", "Hello!"),
         createMessage("me", "Hi!"),
         Message.POISON_PILL,
-        createMessage("late_for_the_party", "Hello? Anyone here?"),
+        createMessage("late_for_the_party", "Hello? Anyone here?")
-    };
+    );
 
-    final MessageQueue queue = new SimpleMessageQueue(messages.length);
+    final var queue = new SimpleMessageQueue(messages.size());
-    for (final Message message : messages) {
+    for (final var message : messages) {
       queue.put(message);
     }
 
@@ -85,7 +84,7 @@ public class ConsumerTest {
    * @return The message instance
    */
   private static Message createMessage(final String sender, final String message) {
-    final SimpleMessage msg = new SimpleMessage();
+    final var msg = new SimpleMessage();
     msg.addHeader(Message.Headers.SENDER, sender);
     msg.addHeader(Message.Headers.DATE, LocalDateTime.now().toString());
     msg.setBody(message);
@@ -106,7 +105,7 @@ public class ConsumerTest {
     }
 
     public boolean logContains(String message) {
-      return log.stream().anyMatch(event -> event.getFormattedMessage().equals(message));
+      return log.stream().map(ILoggingEvent::getFormattedMessage).anyMatch(message::equals);
     }
   }
 

poison-pill/src/test/java/com/iluwatar/poison/pill/PoisonMessageTest.java

@@ -23,12 +23,12 @@
 
 package com.iluwatar.poison.pill;
 
-import org.junit.jupiter.api.Test;
-
 import static com.iluwatar.poison.pill.Message.Headers;
 import static com.iluwatar.poison.pill.Message.POISON_PILL;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/27/15 - 10:30 PM
  *

poison-pill/src/test/java/com/iluwatar/poison/pill/ProducerTest.java

@@ -23,9 +23,6 @@
 
 package com.iluwatar.poison.pill;
 
-import org.junit.jupiter.api.Test;
-import org.mockito.ArgumentCaptor;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.fail;
@@ -35,6 +32,9 @@ import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.verifyZeroInteractions;
 
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+
 /**
  * Date: 12/27/15 - 10:32 PM
  *
@@ -44,16 +44,16 @@ public class ProducerTest {
 
   @Test
   public void testSend() throws Exception {
-    final MqPublishPoint publishPoint = mock(MqPublishPoint.class);
+    final var publishPoint = mock(MqPublishPoint.class);
-    final Producer producer = new Producer("producer", publishPoint);
+    final var producer = new Producer("producer", publishPoint);
     verifyZeroInteractions(publishPoint);
 
     producer.send("Hello!");
 
-    final ArgumentCaptor<Message> messageCaptor = ArgumentCaptor.forClass(Message.class);
+    final var messageCaptor = ArgumentCaptor.forClass(Message.class);
     verify(publishPoint).put(messageCaptor.capture());
 
-    final Message message = messageCaptor.getValue();
+    final var message = messageCaptor.getValue();
     assertNotNull(message);
     assertEquals("producer", message.getHeader(Message.Headers.SENDER));
     assertNotNull(message.getHeader(Message.Headers.DATE));
@@ -64,8 +64,8 @@ public class ProducerTest {
 
   @Test
   public void testStop() throws Exception {
-    final MqPublishPoint publishPoint = mock(MqPublishPoint.class);
+    final var publishPoint = mock(MqPublishPoint.class);
-    final Producer producer = new Producer("producer", publishPoint);
+    final var producer = new Producer("producer", publishPoint);
     verifyZeroInteractions(publishPoint);
 
     producer.stop();
@@ -78,7 +78,7 @@ public class ProducerTest {
       assertNotNull(e);
       assertNotNull(e.getMessage());
       assertEquals("Producer Hello! was stopped and fail to deliver requested message [producer].",
-              e.getMessage());
+          e.getMessage());
     }
 
     verifyNoMoreInteractions(publishPoint);

poison-pill/src/test/java/com/iluwatar/poison/pill/SimpleMessageTest.java

@@ -23,16 +23,14 @@
 
 package com.iluwatar.poison.pill;
 
-import org.junit.jupiter.api.Test;
-
-import java.util.Map;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/27/15 - 10:25 PM
  *
@@ -42,11 +40,11 @@ public class SimpleMessageTest {
 
   @Test
   public void testGetHeaders() {
-    final SimpleMessage message = new SimpleMessage();
+    final var message = new SimpleMessage();
     assertNotNull(message.getHeaders());
     assertTrue(message.getHeaders().isEmpty());
 
-    final String senderName = "test";
+    final var senderName = "test";
     message.addHeader(Message.Headers.SENDER, senderName);
     assertNotNull(message.getHeaders());
     assertFalse(message.getHeaders().isEmpty());
@@ -55,8 +53,8 @@ public class SimpleMessageTest {
 
   @Test
   public void testUnModifiableHeaders() {
-    final SimpleMessage message = new SimpleMessage();
+    final var message = new SimpleMessage();
-    final Map<Message.Headers, String> headers = message.getHeaders();
+    final var headers = message.getHeaders();
     assertThrows(UnsupportedOperationException.class, () -> {
       headers.put(Message.Headers.SENDER, "test");
     });

priority-queue/src/main/java/com/iluwatar/priority/queue/Application.java

@@ -37,22 +37,22 @@ public class Application {
    */
   public static void main(String[] args) throws Exception {
 
-    QueueManager queueManager = new QueueManager(100);
+    var queueManager = new QueueManager(100);
 
     // push some message to queue
     // Low Priority message
-    for (int i = 0; i < 100; i++) {
+    for (var i = 0; i < 100; i++) {
       queueManager.publishMessage(new Message("Low Message Priority", 0));
     }
 
     // High Priority message
-    for (int i = 0; i < 100; i++) {
+    for (var i = 0; i < 100; i++) {
       queueManager.publishMessage(new Message("High Message Priority", 1));
     }
 
 
     // run worker
-    Worker worker = new Worker(queueManager);
+    var worker = new Worker(queueManager);
     worker.run();
 
 

priority-queue/src/main/java/com/iluwatar/priority/queue/PriorityMessageQueue.java

@@ -57,7 +57,7 @@ public class PriorityMessageQueue<T extends Comparable> {
       return null;
     }
 
-    final T root = queue[0];
+    final var root = queue[0];
     queue[0] = queue[size - 1];
     size--;
     maxHeapifyDown();
@@ -83,10 +83,10 @@ public class PriorityMessageQueue<T extends Comparable> {
 
 
   private void maxHeapifyDown() {
-    int index = 0;
+    var index = 0;
     while (hasLeftChild(index)) {
 
-      int smallerIndex = leftChildIndex(index);
+      var smallerIndex = leftChildIndex(index);
 
       if (hasRightChild(index) && right(index).compareTo(left(index)) > 0) {
         smallerIndex = rightChildIndex(index);
@@ -106,7 +106,7 @@ public class PriorityMessageQueue<T extends Comparable> {
   }
 
   private void maxHeapifyUp() {
-    int index = size - 1;
+    var index = size - 1;
     while (hasParent(index) && parent(index).compareTo(queue[index]) < 0) {
       swap(parentIndex(index), index);
       index = parentIndex(index);
@@ -154,7 +154,7 @@ public class PriorityMessageQueue<T extends Comparable> {
   }
 
   private void swap(int fpos, int tpos) {
-    T tmp = queue[fpos];
+    var tmp = queue[fpos];
     queue[fpos] = queue[tpos];
     queue[tpos] = tmp;
   }
@@ -170,7 +170,7 @@ public class PriorityMessageQueue<T extends Comparable> {
    * For debug .. print current state of queue
    */
   public void print() {
-    for (int i = 0; i <= size / 2; i++) {
+    for (var i = 0; i <= size / 2; i++) {
       LOGGER.info(" PARENT : " + queue[i] + " LEFT CHILD : "
           + left(i) + " RIGHT CHILD :" + right(i));
     }

priority-queue/src/main/java/com/iluwatar/priority/queue/QueueManager.java

@@ -33,7 +33,7 @@ public class QueueManager {
   private final PriorityMessageQueue<Message> messagePriorityMessageQueue;
 
   public QueueManager(int initialCapacity) {
-    messagePriorityMessageQueue = new PriorityMessageQueue<Message>(new Message[initialCapacity]);
+    messagePriorityMessageQueue = new PriorityMessageQueue<>(new Message[initialCapacity]);
   }
 
   /**

priority-queue/src/main/java/com/iluwatar/priority/queue/Worker.java

@@ -45,7 +45,7 @@ public class Worker {
   @SuppressWarnings("squid:S2189")
   public void run() throws Exception {
     while (true) {
-      Message message = queueManager.receiveMessage();
+      var message = queueManager.receiveMessage();
       if (message == null) {
         LOGGER.info("No Message ... waiting");
         Thread.sleep(200);

priority-queue/src/test/java/com/iluwatar/priority/queue/PriorityMessageQueueTest.java

@@ -23,11 +23,11 @@
 
 package com.iluwatar.priority.queue;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Test case for order of messages
  */
@@ -36,25 +36,25 @@ public class PriorityMessageQueueTest {
 
   @Test
   public void remove() {
-    PriorityMessageQueue<String> stringPriorityMessageQueue = new PriorityMessageQueue<>(new String[2]);
+    var stringPriorityMessageQueue = new PriorityMessageQueue<>(new String[2]);
-    String pushMessage = "test";
+    var pushMessage = "test";
     stringPriorityMessageQueue.add(pushMessage);
     assertEquals(stringPriorityMessageQueue.remove(), pushMessage);
   }
 
   @Test
   public void add() {
-    PriorityMessageQueue<Integer> stringPriorityMessageQueue = new PriorityMessageQueue<>(new Integer[2]);
+    var stringPriorityMessageQueue = new PriorityMessageQueue<>(new Integer[2]);
     stringPriorityMessageQueue.add(1);
     stringPriorityMessageQueue.add(5);
     stringPriorityMessageQueue.add(10);
     stringPriorityMessageQueue.add(3);
-    assertTrue(stringPriorityMessageQueue.remove() == 10);
+    assertEquals(10, (int) stringPriorityMessageQueue.remove());
   }
 
   @Test
   public void isEmpty() {
-    PriorityMessageQueue<Integer> stringPriorityMessageQueue = new PriorityMessageQueue<>(new Integer[2]);
+    var stringPriorityMessageQueue = new PriorityMessageQueue<>(new Integer[2]);
     assertTrue(stringPriorityMessageQueue.isEmpty());
     stringPriorityMessageQueue.add(1);
     stringPriorityMessageQueue.remove();
@@ -63,12 +63,12 @@ public class PriorityMessageQueueTest {
 
   @Test
   public void testEnsureSize() {
-    PriorityMessageQueue<Integer> stringPriorityMessageQueue = new PriorityMessageQueue<>(new Integer[2]);
+    var stringPriorityMessageQueue = new PriorityMessageQueue<>(new Integer[2]);
     assertTrue(stringPriorityMessageQueue.isEmpty());
     stringPriorityMessageQueue.add(1);
     stringPriorityMessageQueue.add(2);
     stringPriorityMessageQueue.add(2);
     stringPriorityMessageQueue.add(3);
-    assertTrue(stringPriorityMessageQueue.remove() == 3);
+    assertEquals(3, (int) stringPriorityMessageQueue.remove());
   }
 }

priority-queue/src/test/java/com/iluwatar/priority/queue/QueueManagerTest.java

@@ -23,10 +23,10 @@
 
 package com.iluwatar.priority.queue;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Check queue manager
  */
@@ -34,21 +34,21 @@ public class QueueManagerTest {
 
   @Test
   public void publishMessage() {
-    QueueManager queueManager = new QueueManager(2);
+    var queueManager = new QueueManager(2);
-    Message testMessage = new Message("Test Message", 1);
+    var testMessage = new Message("Test Message", 1);
     queueManager.publishMessage(testMessage);
-    Message recivedMessage = queueManager.receiveMessage();
+    var recivedMessage = queueManager.receiveMessage();
     assertEquals(testMessage, recivedMessage);
   }
 
   @Test
   public void receiveMessage() {
-    QueueManager queueManager = new QueueManager(2);
+    var queueManager = new QueueManager(2);
-    Message testMessage1 = new Message("Test Message 1", 1);
+    var testMessage1 = new Message("Test Message 1", 1);
     queueManager.publishMessage(testMessage1);
-    Message testMessage2 = new Message("Test Message 2", 2);
+    var testMessage2 = new Message("Test Message 2", 2);
     queueManager.publishMessage(testMessage2);
-    Message recivedMessage = queueManager.receiveMessage();
+    var recivedMessage = queueManager.receiveMessage();
     assertEquals(testMessage2, recivedMessage);
   }
 }

private-class-data/src/main/java/com/iluwatar/privateclassdata/App.java

@@ -46,13 +46,13 @@ public class App {
    */
   public static void main(String[] args) {
     // stew is mutable
-    Stew stew = new Stew(1, 2, 3, 4);
+    var stew = new Stew(1, 2, 3, 4);
     stew.mix();
     stew.taste();
     stew.mix();
 
     // immutable stew protected with Private Class Data pattern
-    ImmutableStew immutableStew = new ImmutableStew(2, 4, 3, 6);
+    var immutableStew = new ImmutableStew(2, 4, 3, 6);
     immutableStew.mix();
   }
 }

private-class-data/src/test/java/com/iluwatar/privateclassdata/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.privateclassdata;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

private-class-data/src/test/java/com/iluwatar/privateclassdata/ImmutableStewTest.java

@@ -23,13 +23,13 @@
 
 package com.iluwatar.privateclassdata;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import com.iluwatar.privateclassdata.utils.InMemoryAppender;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
 /**
  * Date: 12/27/15 - 10:46 PM
  *
@@ -54,10 +54,10 @@ public class ImmutableStewTest {
    */
   @Test
   public void testMix() {
-    final Stew stew = new Stew(1, 2, 3, 4);
+    var stew = new Stew(1, 2, 3, 4);
-    final String expectedMessage = "Mixing the stew we find: 1 potatoes, 2 carrots, 3 meat and 4 peppers";
+    var expectedMessage = "Mixing the stew we find: 1 potatoes, 2 carrots, 3 meat and 4 peppers";
 
-    for (int i = 0; i < 20; i++) {
+    for (var i = 0; i < 20; i++) {
       stew.mix();
       assertEquals(expectedMessage, appender.getLastMessage());
     }
@@ -70,15 +70,17 @@ public class ImmutableStewTest {
    */
   @Test
   public void testDrink() {
-    final Stew stew = new Stew(1, 2, 3, 4);
+    final var stew = new Stew(1, 2, 3, 4);
     stew.mix();
 
-    assertEquals("Mixing the stew we find: 1 potatoes, 2 carrots, 3 meat and 4 peppers",  appender.getLastMessage());
+    assertEquals("Mixing the stew we find: 1 potatoes, 2 carrots, 3 meat and 4 peppers", appender
+        .getLastMessage());
 
     stew.taste();
-    assertEquals("Tasting the stew",  appender.getLastMessage());
+    assertEquals("Tasting the stew", appender.getLastMessage());
 
     stew.mix();
-    assertEquals("Mixing the stew we find: 0 potatoes, 1 carrots, 2 meat and 3 peppers",  appender.getLastMessage());
+    assertEquals("Mixing the stew we find: 0 potatoes, 1 carrots, 2 meat and 3 peppers", appender
+        .getLastMessage());
   }
 }

private-class-data/src/test/java/com/iluwatar/privateclassdata/StewTest.java

@@ -23,13 +23,13 @@
 
 package com.iluwatar.privateclassdata;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import com.iluwatar.privateclassdata.utils.InMemoryAppender;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
 /**
  * Date: 12/27/15 - 10:46 PM
  *
@@ -54,11 +54,11 @@ public class StewTest {
    */
   @Test
   public void testMix() {
-    final ImmutableStew stew = new ImmutableStew(1, 2, 3, 4);
+    final var stew = new ImmutableStew(1, 2, 3, 4);
-    final String expectedMessage = "Mixing the immutable stew we find: 1 potatoes, "
+    final var expectedMessage = "Mixing the immutable stew we find: 1 potatoes, "
         + "2 carrots, 3 meat and 4 peppers";
 
-    for (int i = 0; i < 20; i++) {
+    for (var i = 0; i < 20; i++) {
       stew.mix();
       assertEquals(expectedMessage, appender.getLastMessage());
     }

private-class-data/src/test/java/com/iluwatar/privateclassdata/utils/InMemoryAppender.java

@@ -26,10 +26,9 @@ package com.iluwatar.privateclassdata.utils;
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.AppenderBase;
-import org.slf4j.LoggerFactory;
-
 import java.util.LinkedList;
 import java.util.List;
+import org.slf4j.LoggerFactory;
 
 /**
  * InMemory Log Appender Util.

producer-consumer/src/main/java/com/iluwatar/producer/consumer/App.java

@@ -26,20 +26,18 @@ package com.iluwatar.producer.consumer;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
  * Producer Consumer Design pattern is a classic concurrency or threading pattern which reduces
- * coupling between Producer and Consumer by separating Identification of work with
+ * coupling between Producer and Consumer by separating Identification of work with Execution of
- * Execution of Work.
+ * Work.
  *
  * <p>In producer consumer design pattern a shared queue is used to control the flow and this
- * separation allows you to code producer and consumer separately. It also addresses the issue
+ * separation allows you to code producer and consumer separately. It also addresses the issue of
- * of different timing require to produce item or consuming item. by using producer consumer
+ * different timing require to produce item or consuming item. by using producer consumer pattern
- * pattern both Producer and Consumer Thread can work with different speed.
+ * both Producer and Consumer Thread can work with different speed.
- * 
  */
 public class App {
 
@@ -47,18 +45,17 @@ public class App {
 
   /**
    * Program entry point.
-   * 
+   *
-   * @param args
+   * @param args command line args
-   *          command line args
    */
   public static void main(String[] args) {
 
-    ItemQueue queue = new ItemQueue();
+    var queue = new ItemQueue();
 
-    ExecutorService executorService = Executors.newFixedThreadPool(5);
+    var executorService = Executors.newFixedThreadPool(5);
-    for (int i = 0; i < 2; i++) {
+    for (var i = 0; i < 2; i++) {
 
-      final Producer producer = new Producer("Producer_" + i, queue);
+      final var producer = new Producer("Producer_" + i, queue);
       executorService.submit(() -> {
         while (true) {
           producer.produce();
@@ -66,8 +63,8 @@ public class App {
       });
     }
 
-    for (int i = 0; i < 3; i++) {
+    for (var i = 0; i < 3; i++) {
-      final Consumer consumer = new Consumer("Consumer_" + i, queue);
+      final var consumer = new Consumer("Consumer_" + i, queue);
       executorService.submit(() -> {
         while (true) {
           consumer.consume();

producer-consumer/src/main/java/com/iluwatar/producer/consumer/Consumer.java

@@ -46,10 +46,9 @@ public class Consumer {
    * Consume item from the queue.
    */
   public void consume() throws InterruptedException {
-
+    var item = queue.take();
-    Item item = queue.take();
     LOGGER.info("Consumer [{}] consume item [{}] produced by [{}]", name,
-            item.getId(), item.getProducer());
+        item.getId(), item.getProducer());
 
   }
 }

producer-consumer/src/main/java/com/iluwatar/producer/consumer/Producer.java

@@ -30,7 +30,7 @@ import java.util.Random;
  * to queue.
  */
 public class Producer {
-  
+
   private static final Random RANDOM = new Random();
 
   private final ItemQueue queue;
@@ -49,7 +49,7 @@ public class Producer {
    */
   public void produce() throws InterruptedException {
 
-    Item item = new Item(name, itemId++);
+    var item = new Item(name, itemId++);
     queue.put(item);
     Thread.sleep(RANDOM.nextInt(2000));
   }

producer-consumer/src/test/java/com/iluwatar/producer/consumer/AppTest.java

@@ -26,16 +26,13 @@ package com.iluwatar.producer.consumer;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
-  public void test() throws Exception {
+  public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
 
   }
 }

producer-consumer/src/test/java/com/iluwatar/producer/consumer/ConsumerTest.java

@@ -23,13 +23,13 @@
 
 package com.iluwatar.producer.consumer;
 
-import org.junit.jupiter.api.Test;
-
 import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/27/15 - 11:01 PM
  *
@@ -41,15 +41,15 @@ public class ConsumerTest {
 
   @Test
   public void testConsume() throws Exception {
-    final ItemQueue queue = spy(new ItemQueue());
+    final var queue = spy(new ItemQueue());
-    for (int id = 0; id < ITEM_COUNT; id++) {
+    for (var id = 0; id < ITEM_COUNT; id++) {
       queue.put(new Item("producer", id));
     }
 
     reset(queue); // Don't count the preparation above as interactions with the queue
-    final Consumer consumer = new Consumer("consumer", queue);
+    final var consumer = new Consumer("consumer", queue);
 
-    for (int id = 0; id < ITEM_COUNT; id++) {
+    for (var id = 0; id < ITEM_COUNT; id++) {
       consumer.consume();
     }
 

producer-consumer/src/test/java/com/iluwatar/producer/consumer/ProducerTest.java

@@ -23,8 +23,6 @@
 
 package com.iluwatar.producer.consumer;
 
-import org.junit.jupiter.api.Test;
-
 import static java.time.Duration.ofMillis;
 import static org.junit.jupiter.api.Assertions.assertTimeout;
 import static org.mockito.Matchers.any;
@@ -32,6 +30,8 @@ import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/28/15 - 12:12 AM
  *
@@ -42,8 +42,8 @@ public class ProducerTest {
   @Test
   public void testProduce() {
     assertTimeout(ofMillis(6000), () -> {
-      final ItemQueue queue = mock(ItemQueue.class);
+      final var queue = mock(ItemQueue.class);
-      final Producer producer = new Producer("producer", queue);
+      final var producer = new Producer("producer", queue);
 
       producer.produce();
       verify(queue).put(any(Item.class));

promise/src/main/java/com/iluwatar/promise/App.java

@@ -29,19 +29,18 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * The Promise object is used for asynchronous computations. A Promise represents an operation
+ * The Promise object is used for asynchronous computations. A Promise represents an operation that
- * that hasn't completed yet, but is expected in the future.
+ * hasn't completed yet, but is expected in the future.
  *
- * <p>A Promise represents a proxy for a value not necessarily known when the promise is created. It
+ * <p>A Promise represents a proxy for a value not necessarily known when the promise is created.
- * allows you to associate dependent promises to an asynchronous action's eventual success value or
+ * It allows you to associate dependent promises to an asynchronous action's eventual success value
- * failure reason. This lets asynchronous methods return values like synchronous methods: instead 
+ * or failure reason. This lets asynchronous methods return values like synchronous methods: instead
- * of the final value, the asynchronous method returns a promise of having a value at some point 
+ * of the final value, the asynchronous method returns a promise of having a value at some point in
- * in the future.
+ * the future.
  *
  * <p>Promises provide a few advantages over callback objects:
  * <ul>
@@ -58,14 +57,15 @@ import org.slf4j.LoggerFactory;
  * a file download promise, then a promise of character frequency, then a promise of lowest
  * frequency character which is finally consumed and result is printed on console.
  * </ul>
- * 
+ *
  * @see CompletableFuture
  */
 public class App {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
 
-  private static final String DEFAULT_URL = "https://raw.githubusercontent.com/iluwatar/java-design-patterns/master/promise/README.md";
+  private static final String DEFAULT_URL =
+      "https://raw.githubusercontent.com/iluwatar/java-design-patterns/master/promise/README.md";
   private final ExecutorService executor;
   private final CountDownLatch stopLatch;
 
@@ -76,12 +76,13 @@ public class App {
 
   /**
    * Program entry point.
+   *
    * @param args arguments
    * @throws InterruptedException if main thread is interrupted.
-   * @throws ExecutionException if an execution error occurs.
+   * @throws ExecutionException   if an execution error occurs.
    */
   public static void main(String[] args) throws InterruptedException, ExecutionException {
-    App app = new App();
+    var app = new App();
     try {
       app.promiseUsage();
     } finally {
@@ -100,13 +101,12 @@ public class App {
    * consume the result in a Consumer<Character>
    */
   private void calculateLowestFrequencyChar() {
-    lowestFrequencyChar()
+    lowestFrequencyChar().thenAccept(
-        .thenAccept(
+        charFrequency -> {
-          charFrequency -> {
+          LOGGER.info("Char with lowest frequency is: {}", charFrequency);
-            LOGGER.info("Char with lowest frequency is: {}", charFrequency);
+          taskCompleted();
-            taskCompleted();
+        }
-          }
+    );
-      );
   }
 
   /*
@@ -114,13 +114,12 @@ public class App {
    * in a Consumer<Integer>
    */
   private void calculateLineCount() {
-    countLines()
+    countLines().thenAccept(
-        .thenAccept(
+        count -> {
-          count -> {
+          LOGGER.info("Line count is: {}", count);
-            LOGGER.info("Line count is: {}", count);
+          taskCompleted();
-            taskCompleted();
+        }
-          }
+    );
-      );
   }
 
   /*
@@ -128,17 +127,15 @@ public class App {
    * then promise to apply function to calculate lowest character frequency.
    */
   private Promise<Character> lowestFrequencyChar() {
-    return characterFrequency()
+    return characterFrequency().thenApply(Utility::lowestFrequencyChar);
-        .thenApply(Utility::lowestFrequencyChar);
   }
 
   /*
    * Download the file at DEFAULT_URL and when that promise is fulfilled,
    * then promise to apply function to calculate character frequency.
    */
-  private Promise<Map<Character, Integer>> characterFrequency() {
+  private Promise<Map<Character, Long>> characterFrequency() {
-    return download(DEFAULT_URL)
+    return download(DEFAULT_URL).thenApply(Utility::characterFrequency);
-        .thenApply(Utility::characterFrequency);
   }
 
   /*
@@ -146,8 +143,7 @@ public class App {
    * then promise to apply function to count lines in that file.
    */
   private Promise<Integer> countLines() {
-    return download(DEFAULT_URL)
+    return download(DEFAULT_URL).thenApply(Utility::countLines);
-        .thenApply(Utility::countLines);
   }
 
   /*

promise/src/main/java/com/iluwatar/promise/Promise.java

@@ -32,10 +32,10 @@ import java.util.function.Function;
 /**
  * A Promise represents a proxy for a value not necessarily known when the promise is created. It
  * allows you to associate dependent promises to an asynchronous action's eventual success value or
- * failure reason. This lets asynchronous methods return values like synchronous methods: instead 
+ * failure reason. This lets asynchronous methods return values like synchronous methods: instead of
- * of the final value, the asynchronous method returns a promise of having a value at some point 
+ * the final value, the asynchronous method returns a promise of having a value at some point in the
- * in the future.
+ * future.
- * 
+ *
  * @param <T> type of result.
  */
 public class Promise<T> extends PromiseSupport<T> {
@@ -51,6 +51,7 @@ public class Promise<T> extends PromiseSupport<T> {
 
   /**
    * Fulfills the promise with the provided value.
+   *
    * @param value the fulfilled value that can be accessed using {@link #get()}.
    */
   @Override
@@ -61,8 +62,9 @@ public class Promise<T> extends PromiseSupport<T> {
 
   /**
    * Fulfills the promise with exception due to error in execution.
-   * @param exception the exception will be wrapped in {@link ExecutionException}
+   *
-   *        when accessing the value using {@link #get()}.
+   * @param exception the exception will be wrapped in {@link ExecutionException} when accessing the
+   *                  value using {@link #get()}.
    */
   @Override
   public void fulfillExceptionally(Exception exception) {
@@ -86,10 +88,10 @@ public class Promise<T> extends PromiseSupport<T> {
   }
 
   /**
-   * Executes the task using the executor in other thread and fulfills the promise returned
+   * Executes the task using the executor in other thread and fulfills the promise returned once the
-   * once the task completes either successfully or with an exception.
+   * task completes either successfully or with an exception.
-   * 
+   *
-   * @param task the task that will provide the value to fulfill the promise.
+   * @param task     the task that will provide the value to fulfill the promise.
    * @param executor the executor in which the task should be run.
    * @return a promise that represents the result of running the task provided.
    */
@@ -105,21 +107,23 @@ public class Promise<T> extends PromiseSupport<T> {
   }
 
   /**
-   * Returns a new promise that, when this promise is fulfilled normally, is fulfilled with 
+   * Returns a new promise that, when this promise is fulfilled normally, is fulfilled with result
-   * result of this promise as argument to the action provided.
+   * of this promise as argument to the action provided.
+   *
    * @param action action to be executed.
    * @return a new promise.
    */
   public Promise<Void> thenAccept(Consumer<? super T> action) {
-    Promise<Void> dest = new Promise<>();
+    var dest = new Promise<Void>();
     fulfillmentAction = new ConsumeAction(this, dest, action);
     return dest;
   }
-  
+
   /**
    * Set the exception handler on this promise.
-   * @param exceptionHandler a consumer that will handle the exception occurred while fulfilling
+   *
-   *            the promise.
+   * @param exceptionHandler a consumer that will handle the exception occurred while fulfilling the
+   *                         promise.
    * @return this
    */
   public Promise<T> onError(Consumer<? super Throwable> exceptionHandler) {
@@ -128,8 +132,9 @@ public class Promise<T> extends PromiseSupport<T> {
   }
 
   /**
-   * Returns a new promise that, when this promise is fulfilled normally, is fulfilled with 
+   * Returns a new promise that, when this promise is fulfilled normally, is fulfilled with result
-   * result of this promise as argument to the function provided.
+   * of this promise as argument to the function provided.
+   *
    * @param func function to be executed.
    * @return a new promise.
    */
@@ -140,8 +145,8 @@ public class Promise<T> extends PromiseSupport<T> {
   }
 
   /**
-   * Accesses the value from source promise and calls the consumer, then fulfills the
+   * Accesses the value from source promise and calls the consumer, then fulfills the destination
-   * destination promise.
+   * promise.
    */
   private class ConsumeAction implements Runnable {
 

promise/src/main/java/com/iluwatar/promise/PromiseSupport.java

@@ -27,16 +27,15 @@ import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * A really simplified implementation of future that allows completing it successfully with a value 
+ * A really simplified implementation of future that allows completing it successfully with a value
  * or exceptionally with an exception.
  */
 class PromiseSupport<T> implements Future<T> {
-  
+
   private static final Logger LOGGER = LoggerFactory.getLogger(PromiseSupport.class);
 
   private static final int RUNNING = 1;
@@ -93,13 +92,12 @@ class PromiseSupport<T> implements Future<T> {
     }
     if (state == COMPLETED) {
       return value;
-    } 
+    }
     throw new ExecutionException(exception);
   }
 
   @Override
-  public T get(long timeout, TimeUnit unit)
+  public T get(long timeout, TimeUnit unit) throws ExecutionException {
-      throws  ExecutionException, TimeoutException {
     synchronized (lock) {
       while (state == RUNNING) {
         try {
@@ -110,10 +108,10 @@ class PromiseSupport<T> implements Future<T> {
         }
       }
     }
-    
+
     if (state == COMPLETED) {
       return value;
-    } 
+    }
     throw new ExecutionException(exception);
   }
 }

promise/src/main/java/com/iluwatar/promise/Utility.java

@@ -29,13 +29,13 @@ import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.io.InputStreamReader;
-import java.io.Reader;
 import java.net.URL;
-import java.util.HashMap;
+import java.util.Collections;
-import java.util.Iterator;
+import java.util.Comparator;
 import java.util.Map;
 import java.util.Map.Entry;
-
+import java.util.function.Function;
+import java.util.stream.Collectors;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -48,86 +48,68 @@ public class Utility {
 
   /**
    * Calculates character frequency of the file provided.
+   *
    * @param fileLocation location of the file.
    * @return a map of character to its frequency, an empty map if file does not exist.
    */
-  public static Map<Character, Integer> characterFrequency(String fileLocation) {
+  public static Map<Character, Long> characterFrequency(String fileLocation) {
-    Map<Character, Integer> characterToFrequency = new HashMap<>();
+    try (var bufferedReader = new BufferedReader(new FileReader(fileLocation))) {
-    try (Reader reader = new FileReader(fileLocation);
+      return bufferedReader.lines()
-        BufferedReader bufferedReader = new BufferedReader(reader)) {
+          .flatMapToInt(String::chars)
-      for (String line; (line = bufferedReader.readLine()) != null;) {
+          .mapToObj(x -> (char) x)
-        for (char c : line.toCharArray()) {
+          .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
-          if (!characterToFrequency.containsKey(c)) {
-            characterToFrequency.put(c, 1);
-          } else {
-            characterToFrequency.put(c, characterToFrequency.get(c) + 1);
-          }
-        }
-      }
     } catch (IOException ex) {
       ex.printStackTrace();
     }
-    return characterToFrequency;
+    return Collections.emptyMap();
   }
 
   /**
    * Return the character with the lowest frequency, if exists.
+   *
    * @return the character, {@code Optional.empty()} otherwise.
    */
-  public static Character lowestFrequencyChar(Map<Character, Integer> charFrequency) {
+  public static Character lowestFrequencyChar(Map<Character, Long> charFrequency) {
-    Character lowestFrequencyChar = null;
+    return charFrequency
-    Iterator<Entry<Character, Integer>> iterator = charFrequency.entrySet().iterator();
+        .entrySet()
-    Entry<Character, Integer> entry = iterator.next();
+        .stream()
-    int minFrequency = entry.getValue();
+        .min(Comparator.comparingLong(Entry::getValue))
-    lowestFrequencyChar = entry.getKey();
+        .map(Entry::getKey)
-
+        .orElseThrow();
-    while (iterator.hasNext()) {
-      entry = iterator.next();
-      if (entry.getValue() < minFrequency) {
-        minFrequency = entry.getValue();
-        lowestFrequencyChar = entry.getKey();
-      }
-    }
-
-    return lowestFrequencyChar;
   }
 
   /**
    * Count the number of lines in a file.
+   *
    * @return number of lines, 0 if file does not exist.
    */
   public static Integer countLines(String fileLocation) {
-    int lineCount = 0;
+    try (var bufferedReader = new BufferedReader(new FileReader(fileLocation))) {
-    try (Reader reader = new FileReader(fileLocation);
+      return (int) bufferedReader.lines().count();
-        BufferedReader bufferedReader = new BufferedReader(reader)) {
-      while (bufferedReader.readLine() != null) {
-        lineCount++;
-      }
     } catch (IOException ex) {
       ex.printStackTrace();
     }
-    return lineCount;
+    return 0;
   }
 
   /**
    * Downloads the contents from the given urlString, and stores it in a temporary directory.
+   *
    * @return the absolute path of the file downloaded.
    */
   public static String downloadFile(String urlString) throws IOException {
     LOGGER.info("Downloading contents from url: {}", urlString);
-    URL url = new URL(urlString);
+    var url = new URL(urlString);
-    File file = File.createTempFile("promise_pattern", null);
+    var file = File.createTempFile("promise_pattern", null);
-    try (Reader reader = new InputStreamReader(url.openStream());
+    try (var bufferedReader = new BufferedReader(new InputStreamReader(url.openStream()));
-        BufferedReader bufferedReader = new BufferedReader(reader);
+         var writer = new FileWriter(file)) {
-        FileWriter writer = new FileWriter(file)) {
+      String line;
-      for (String line; (line = bufferedReader.readLine()) != null; ) {
+      while ((line = bufferedReader.readLine()) != null) {
         writer.write(line);
         writer.write("\n");
       }
       LOGGER.info("File downloaded at: {}", file.getAbsolutePath());
       return file.getAbsolutePath();
-    } catch (IOException ex) {
-      throw ex;
     }
   }
 }

promise/src/test/java/com/iluwatar/promise/AppTest.java

@@ -23,12 +23,10 @@
 
 package com.iluwatar.promise;
 
+import java.util.concurrent.ExecutionException;
 import org.junit.jupiter.api.Test;
 
-import java.util.concurrent.ExecutionException;
-
 /**
- * 
  * Application test.
  */
 public class AppTest {

promise/src/test/java/com/iluwatar/promise/PromiseTest.java

@@ -23,8 +23,13 @@
 
 package com.iluwatar.promise;
 
-import org.junit.jupiter.api.BeforeEach;
+import static org.junit.jupiter.api.Assertions.assertEquals;
-import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
+import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
 
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
@@ -33,15 +38,8 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.function.Consumer;
-import java.util.function.Function;
+import org.junit.jupiter.api.BeforeEach;
-
+import org.junit.jupiter.api.Test;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.fail;
-import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.verify;
 
 /**
  * Tests Promise class.
@@ -58,7 +56,7 @@ public class PromiseTest {
   }
 
   @Test
-  public void promiseIsFulfilledWithTheResultantValueOfExecutingTheTask() 
+  public void promiseIsFulfilledWithTheResultantValueOfExecutingTheTask()
       throws InterruptedException, ExecutionException {
     promise.fulfillInAsync(new NumberCrunchingTask(), executor);
 
@@ -66,21 +64,20 @@ public class PromiseTest {
     assertTrue(promise.isDone());
     assertFalse(promise.isCancelled());
   }
-  
+
   @Test
-  public void promiseIsFulfilledWithAnExceptionIfTaskThrowsAnException() 
+  public void promiseIsFulfilledWithAnExceptionIfTaskThrowsAnException()
-      throws InterruptedException, ExecutionException, TimeoutException {
+      throws InterruptedException, TimeoutException {
     testWaitingForeverForPromiseToBeFulfilled();
     testWaitingSomeTimeForPromiseToBeFulfilled();
   }
 
-  private void testWaitingForeverForPromiseToBeFulfilled() 
+  private void testWaitingForeverForPromiseToBeFulfilled() throws InterruptedException {
-      throws InterruptedException, TimeoutException {
+    var promise = new Promise<Integer>();
-    Promise<Integer> promise = new Promise<>();
     promise.fulfillInAsync(() -> {
       throw new RuntimeException("Barf!");
     }, executor);
-    
+
     try {
       promise.get();
       fail("Fetching promise should result in exception if the task threw an exception");
@@ -88,7 +85,7 @@ public class PromiseTest {
       assertTrue(promise.isDone());
       assertFalse(promise.isCancelled());
     }
-    
+
     try {
       promise.get(1000, TimeUnit.SECONDS);
       fail("Fetching promise should result in exception if the task threw an exception");
@@ -97,14 +94,13 @@ public class PromiseTest {
       assertFalse(promise.isCancelled());
     }
   }
-  
+
-  private void testWaitingSomeTimeForPromiseToBeFulfilled() 
+  private void testWaitingSomeTimeForPromiseToBeFulfilled() throws InterruptedException {
-      throws InterruptedException, TimeoutException {
+    var promise = new Promise<Integer>();
-    Promise<Integer> promise = new Promise<>();
     promise.fulfillInAsync(() -> {
       throw new RuntimeException("Barf!");
     }, executor);
-    
+
     try {
       promise.get(1000, TimeUnit.SECONDS);
       fail("Fetching promise should result in exception if the task threw an exception");
@@ -112,7 +108,7 @@ public class PromiseTest {
       assertTrue(promise.isDone());
       assertFalse(promise.isCancelled());
     }
-    
+
     try {
       promise.get();
       fail("Fetching promise should result in exception if the task threw an exception");
@@ -120,18 +116,15 @@ public class PromiseTest {
       assertTrue(promise.isDone());
       assertFalse(promise.isCancelled());
     }
-    
+
   }
 
   @Test
-  public void dependentPromiseIsFulfilledAfterTheConsumerConsumesTheResultOfThisPromise() 
+  public void dependentPromiseIsFulfilledAfterTheConsumerConsumesTheResultOfThisPromise()
       throws InterruptedException, ExecutionException {
-    Promise<Void> dependentPromise = promise
+    var dependentPromise = promise
         .fulfillInAsync(new NumberCrunchingTask(), executor)
-        .thenAccept(value -> {
+        .thenAccept(value -> assertEquals(NumberCrunchingTask.CRUNCHED_NUMBER, value));
-          assertEquals(NumberCrunchingTask.CRUNCHED_NUMBER, value);
-        });
-
 
     dependentPromise.get();
     assertTrue(dependentPromise.isDone());
@@ -139,9 +132,9 @@ public class PromiseTest {
   }
 
   @Test
-  public void dependentPromiseIsFulfilledWithAnExceptionIfConsumerThrowsAnException() 
+  public void dependentPromiseIsFulfilledWithAnExceptionIfConsumerThrowsAnException()
-      throws InterruptedException, ExecutionException, TimeoutException {
+      throws InterruptedException {
-    Promise<Void> dependentPromise = promise
+    var dependentPromise = promise
         .fulfillInAsync(new NumberCrunchingTask(), executor)
         .thenAccept(value -> {
           throw new RuntimeException("Barf!");
@@ -155,7 +148,7 @@ public class PromiseTest {
       assertTrue(promise.isDone());
       assertFalse(promise.isCancelled());
     }
-    
+
     try {
       dependentPromise.get(1000, TimeUnit.SECONDS);
       fail("Fetching dependent promise should result in exception "
@@ -167,12 +160,12 @@ public class PromiseTest {
   }
 
   @Test
-  public void dependentPromiseIsFulfilledAfterTheFunctionTransformsTheResultOfThisPromise() 
+  public void dependentPromiseIsFulfilledAfterTheFunctionTransformsTheResultOfThisPromise()
       throws InterruptedException, ExecutionException {
-    Promise<String> dependentPromise = promise
+    var dependentPromise = promise
         .fulfillInAsync(new NumberCrunchingTask(), executor)
         .thenApply(value -> {
-          assertEquals(NumberCrunchingTask.CRUNCHED_NUMBER, value); 
+          assertEquals(NumberCrunchingTask.CRUNCHED_NUMBER, value);
           return String.valueOf(value);
         });
 
@@ -181,11 +174,11 @@ public class PromiseTest {
     assertTrue(dependentPromise.isDone());
     assertFalse(dependentPromise.isCancelled());
   }
-  
+
   @Test
-  public void dependentPromiseIsFulfilledWithAnExceptionIfTheFunctionThrowsException() 
+  public void dependentPromiseIsFulfilledWithAnExceptionIfTheFunctionThrowsException()
-      throws InterruptedException, ExecutionException, TimeoutException {
+      throws InterruptedException {
-    Promise<String> dependentPromise = promise
+    var dependentPromise = promise
         .fulfillInAsync(new NumberCrunchingTask(), executor)
         .thenApply(value -> {
           throw new RuntimeException("Barf!");
@@ -199,7 +192,7 @@ public class PromiseTest {
       assertTrue(promise.isDone());
       assertFalse(promise.isCancelled());
     }
-    
+
     try {
       dependentPromise.get(1000, TimeUnit.SECONDS);
       fail("Fetching dependent promise should result in exception "
@@ -209,26 +202,26 @@ public class PromiseTest {
       assertFalse(promise.isCancelled());
     }
   }
-  
+
   @Test
-  public void fetchingAnAlreadyFulfilledPromiseReturnsTheFulfilledValueImmediately() 
+  public void fetchingAnAlreadyFulfilledPromiseReturnsTheFulfilledValueImmediately()
-      throws InterruptedException, ExecutionException, TimeoutException {
+      throws ExecutionException {
-    Promise<Integer> promise = new Promise<>();
+    var promise = new Promise<Integer>();
     promise.fulfill(NumberCrunchingTask.CRUNCHED_NUMBER);
-    
+
     promise.get(1000, TimeUnit.SECONDS);
   }
-  
+
   @SuppressWarnings("unchecked")
   @Test
   public void exceptionHandlerIsCalledWhenPromiseIsFulfilledExceptionally() {
-    Promise<Object> promise = new Promise<>();
+    var promise = new Promise<>();
-    Consumer<Throwable> exceptionHandler = mock(Consumer.class);
+    var exceptionHandler = mock(Consumer.class);
     promise.onError(exceptionHandler);
-    
+
-    Exception exception = new Exception("barf!");
+    var exception = new Exception("barf!");
     promise.fulfillExceptionally(exception);
-    
+
     verify(exceptionHandler).accept(eq(exception));
   }
 

property/src/main/java/com/iluwatar/property/App.java

@@ -49,36 +49,36 @@ public class App {
    */
   public static void main(String[] args) {
     /* set up */
-    Prototype charProto = new Character();
+    var charProto = new Character();
     charProto.set(Stats.STRENGTH, 10);
     charProto.set(Stats.AGILITY, 10);
     charProto.set(Stats.ARMOR, 10);
     charProto.set(Stats.ATTACK_POWER, 10);
 
-    Character mageProto = new Character(Type.MAGE, charProto);
+    var mageProto = new Character(Type.MAGE, charProto);
     mageProto.set(Stats.INTELLECT, 15);
     mageProto.set(Stats.SPIRIT, 10);
 
-    Character warProto = new Character(Type.WARRIOR, charProto);
+    var warProto = new Character(Type.WARRIOR, charProto);
     warProto.set(Stats.RAGE, 15);
     warProto.set(Stats.ARMOR, 15); // boost default armor for warrior
 
-    Character rogueProto = new Character(Type.ROGUE, charProto);
+    var rogueProto = new Character(Type.ROGUE, charProto);
     rogueProto.set(Stats.ENERGY, 15);
     rogueProto.set(Stats.AGILITY, 15); // boost default agility for rogue
 
     /* usage */
-    Character mag = new Character("Player_1", mageProto);
+    var mag = new Character("Player_1", mageProto);
     mag.set(Stats.ARMOR, 8);
     LOGGER.info(mag.toString());
 
-    Character warrior = new Character("Player_2", warProto);
+    var warrior = new Character("Player_2", warProto);
     LOGGER.info(warrior.toString());
 
-    Character rogue = new Character("Player_3", rogueProto);
+    var rogue = new Character("Player_3", rogueProto);
     LOGGER.info(rogue.toString());
 
-    Character rogueDouble = new Character("Player_4", rogue);
+    var rogueDouble = new Character("Player_4", rogue);
     rogueDouble.set(Stats.ATTACK_POWER, 12);
     LOGGER.info(rogueDouble.toString());
   }

property/src/main/java/com/iluwatar/property/Character.java

@@ -93,7 +93,7 @@ public class Character implements Prototype {
 
   @Override
   public Integer get(Stats stat) {
-    boolean containsValue = properties.containsKey(stat);
+    var containsValue = properties.containsKey(stat);
     if (containsValue) {
       return properties.get(stat);
     } else {
@@ -118,7 +118,7 @@ public class Character implements Prototype {
 
   @Override
   public String toString() {
-    StringBuilder builder = new StringBuilder();
+    var builder = new StringBuilder();
     if (name != null) {
       builder.append("Player: ").append(name).append('\n');
     }
@@ -128,8 +128,8 @@ public class Character implements Prototype {
     }
 
     builder.append("Stats:\n");
-    for (Stats stat : Stats.values()) {
+    for (var stat : Stats.values()) {
-      Integer value = this.get(stat);
+      var value = this.get(stat);
       if (value == null) {
         continue;
       }

property/src/test/java/com/iluwatar/property/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.property;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

property/src/test/java/com/iluwatar/property/CharacterTest.java

@@ -23,14 +23,15 @@
 
 package com.iluwatar.property;
 
-import org.junit.jupiter.api.Test;
-
 import static com.iluwatar.property.Character.Type;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.util.Arrays;
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/28/15 - 7:46 PM
  *
@@ -40,13 +41,13 @@ public class CharacterTest {
 
   @Test
   public void testPrototypeStats() throws Exception {
-    final Character prototype = new Character();
+    final var prototype = new Character();
 
-    for (final Stats stat : Stats.values()) {
+    for (final var stat : Stats.values()) {
       assertFalse(prototype.has(stat));
       assertNull(prototype.get(stat));
 
-      final Integer expectedValue = stat.ordinal();
+      final var expectedValue = stat.ordinal();
       prototype.set(stat, expectedValue);
       assertTrue(prototype.has(stat));
       assertEquals(expectedValue, prototype.get(stat));
@@ -59,15 +60,13 @@ public class CharacterTest {
   }
 
   @Test
-  public void testCharacterStats() throws Exception {
+  public void testCharacterStats() {
-    final Character prototype = new Character();
+    final var prototype = new Character();
-    for (final Stats stat : Stats.values()) {
+    Arrays.stream(Stats.values()).forEach(stat -> prototype.set(stat, stat.ordinal()));
-      prototype.set(stat, stat.ordinal());
-    }
 
-    final Character mage = new Character(Type.MAGE, prototype);
+    final var mage = new Character(Type.MAGE, prototype);
-    for (final Stats stat : Stats.values()) {
+    for (final var stat : Stats.values()) {
-      final Integer expectedValue = stat.ordinal();
+      final var expectedValue = stat.ordinal();
       assertTrue(mage.has(stat));
       assertEquals(expectedValue, mage.get(stat));
     }
@@ -75,17 +74,17 @@ public class CharacterTest {
 
   @Test
   public void testToString() {
-    final Character prototype = new Character();
+    final var prototype = new Character();
     prototype.set(Stats.ARMOR, 1);
     prototype.set(Stats.AGILITY, 2);
     prototype.set(Stats.INTELLECT, 3);
     assertEquals("Stats:\n - AGILITY:2\n - ARMOR:1\n - INTELLECT:3\n", prototype.toString());
 
-    final Character stupid = new Character(Type.ROGUE, prototype);
+    final var stupid = new Character(Type.ROGUE, prototype);
     stupid.remove(Stats.INTELLECT);
     assertEquals("Character type: ROGUE\nStats:\n - AGILITY:2\n - ARMOR:1\n", stupid.toString());
 
-    final Character weak = new Character("weak", prototype);
+    final var weak = new Character("weak", prototype);
     weak.remove(Stats.ARMOR);
     assertEquals("Player: weak\nStats:\n - AGILITY:2\n - INTELLECT:3\n", weak.toString());
 
@@ -93,32 +92,32 @@ public class CharacterTest {
 
   @Test
   public void testName() {
-    final Character prototype = new Character();
+    final var prototype = new Character();
     prototype.set(Stats.ARMOR, 1);
     prototype.set(Stats.INTELLECT, 2);
     assertNull(prototype.name());
 
-    final Character stupid = new Character(Type.ROGUE, prototype);
+    final var stupid = new Character(Type.ROGUE, prototype);
     stupid.remove(Stats.INTELLECT);
     assertNull(stupid.name());
 
-    final Character weak = new Character("weak", prototype);
+    final var weak = new Character("weak", prototype);
     weak.remove(Stats.ARMOR);
     assertEquals("weak", weak.name());
   }
 
   @Test
   public void testType() {
-    final Character prototype = new Character();
+    final var prototype = new Character();
     prototype.set(Stats.ARMOR, 1);
     prototype.set(Stats.INTELLECT, 2);
     assertNull(prototype.type());
 
-    final Character stupid = new Character(Type.ROGUE, prototype);
+    final var stupid = new Character(Type.ROGUE, prototype);
     stupid.remove(Stats.INTELLECT);
     assertEquals(Type.ROGUE, stupid.type());
 
-    final Character weak = new Character("weak", prototype);
+    final var weak = new Character("weak", prototype);
     weak.remove(Stats.ARMOR);
     assertNull(weak.type());
   }

prototype/README.md

@@ -52,11 +52,11 @@ class Sheep implements Cloneable {
 Then it can be cloned like below
 
 ```java
-Sheep original = new Sheep("Jolly");
+var original = new Sheep("Jolly");
 System.out.println(original.getName()); // Jolly
 
 // Clone and modify what is required
-Sheep cloned = original.clone();
+var cloned = original.clone();
 cloned.setName("Dolly");
 System.out.println(cloned.getName()); // Dolly
 ```

prototype/src/main/java/com/iluwatar/prototype/App.java

@@ -46,24 +46,23 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
-    HeroFactory factory = new HeroFactoryImpl(
+    var factory = new HeroFactoryImpl(
         new ElfMage("cooking"),
         new ElfWarlord("cleaning"),
         new ElfBeast("protecting")
     );
-    Mage mage = factory.createMage();
+    var mage = factory.createMage();
-    Warlord warlord = factory.createWarlord();
+    var warlord = factory.createWarlord();
-    Beast beast = factory.createBeast();
+    var beast = factory.createBeast();
     LOGGER.info(mage.toString());
     LOGGER.info(warlord.toString());
     LOGGER.info(beast.toString());
 
-    factory =
+    factory = new HeroFactoryImpl(
-        new HeroFactoryImpl(
+        new OrcMage("axe"),
-            new OrcMage("axe"),
+        new OrcWarlord("sword"),
-            new OrcWarlord("sword"),
+        new OrcBeast("laser")
-            new OrcBeast("laser")
+    );
-        );
     mage = factory.createMage();
     warlord = factory.createWarlord();
     beast = factory.createBeast();

prototype/src/main/java/com/iluwatar/prototype/Beast.java

@@ -28,9 +28,11 @@ package com.iluwatar.prototype;
  */
 public abstract class Beast implements Prototype {
 
-  public Beast() { }
+  public Beast() {
+  }
 
-  public Beast(Beast source) { }
+  public Beast(Beast source) {
+  }
 
   @Override
   public abstract Beast copy();

prototype/src/main/java/com/iluwatar/prototype/ElfBeast.java

@@ -60,15 +60,11 @@ public class ElfBeast extends Beast {
     if (getClass() != obj.getClass()) {
       return false;
     }
-    ElfBeast other = (ElfBeast) obj;
+    var other = (ElfBeast) obj;
     if (helpType == null) {
-      if (other.helpType != null) {
+      return other.helpType == null;
-        return false;
-      }
-    } else if (!helpType.equals(other.helpType)) {
-      return false;
     }
-    return true;
+    return helpType.equals(other.helpType);
   }
 
 }

prototype/src/main/java/com/iluwatar/prototype/ElfMage.java

@@ -60,14 +60,10 @@ public class ElfMage extends Mage {
     if (getClass() != obj.getClass()) {
       return false;
     }
-    ElfMage other = (ElfMage) obj;
+    var other = (ElfMage) obj;
     if (helpType == null) {
-      if (other.helpType != null) {
+      return other.helpType == null;
-        return false;
-      }
-    } else if (!helpType.equals(other.helpType)) {
-      return false;
     }
-    return true;
+    return helpType.equals(other.helpType);
   }
 }

prototype/src/main/java/com/iluwatar/prototype/ElfWarlord.java

@@ -60,14 +60,10 @@ public class ElfWarlord extends Warlord {
     if (getClass() != obj.getClass()) {
       return false;
     }
-    ElfWarlord other = (ElfWarlord) obj;
+    var other = (ElfWarlord) obj;
     if (helpType == null) {
-      if (other.helpType != null) {
+      return other.helpType == null;
-        return false;
-      }
-    } else if (!helpType.equals(other.helpType)) {
-      return false;
     }
-    return true;
+    return helpType.equals(other.helpType);
   }
 }

prototype/src/main/java/com/iluwatar/prototype/Mage.java

@@ -28,9 +28,11 @@ package com.iluwatar.prototype;
  */
 public abstract class Mage implements Prototype {
 
-  public Mage() { }
+  public Mage() {
+  }
 
-  public Mage(Mage source) { }
+  public Mage(Mage source) {
+  }
 
   @Override
   public abstract Mage copy();

prototype/src/main/java/com/iluwatar/prototype/OrcBeast.java

@@ -60,15 +60,11 @@ public class OrcBeast extends Beast {
     if (getClass() != obj.getClass()) {
       return false;
     }
-    OrcBeast other = (OrcBeast) obj;
+    var other = (OrcBeast) obj;
     if (weapon == null) {
-      if (other.weapon != null) {
+      return other.weapon == null;
-        return false;
-      }
-    } else if (!weapon.equals(other.weapon)) {
-      return false;
     }
-    return true;
+    return weapon.equals(other.weapon);
   }
 
 

prototype/src/main/java/com/iluwatar/prototype/OrcMage.java

@@ -60,14 +60,10 @@ public class OrcMage extends Mage {
     if (getClass() != obj.getClass()) {
       return false;
     }
-    OrcMage other = (OrcMage) obj;
+    var other = (OrcMage) obj;
     if (weapon == null) {
-      if (other.weapon != null) {
+      return other.weapon == null;
-        return false;
-      }
-    } else if (!weapon.equals(other.weapon)) {
-      return false;
     }
-    return true;
+    return weapon.equals(other.weapon);
   }
 }

prototype/src/main/java/com/iluwatar/prototype/OrcWarlord.java

@@ -60,14 +60,10 @@ public class OrcWarlord extends Warlord {
     if (getClass() != obj.getClass()) {
       return false;
     }
-    OrcWarlord other = (OrcWarlord) obj;
+    var other = (OrcWarlord) obj;
     if (weapon == null) {
-      if (other.weapon != null) {
+      return other.weapon == null;
-        return false;
-      }
-    } else if (!weapon.equals(other.weapon)) {
-      return false;
     }
-    return true;
+    return weapon.equals(other.weapon);
   }
 }

prototype/src/main/java/com/iluwatar/prototype/Warlord.java

@@ -28,9 +28,11 @@ package com.iluwatar.prototype;
  */
 public abstract class Warlord implements Prototype {
 
-  public Warlord() { }
+  public Warlord() {
+  }
 
-  public Warlord(Warlord source) { }
+  public Warlord(Warlord source) {
+  }
 
   @Override
   public abstract Warlord copy();

prototype/src/test/java/com/iluwatar/prototype/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.prototype;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

prototype/src/test/java/com/iluwatar/prototype/PrototypeTest.java

@@ -23,37 +23,40 @@
 
 package com.iluwatar.prototype;
 
-import org.junit.jupiter.params.ParameterizedTest;
+import static org.junit.jupiter.api.Assertions.assertEquals;
-import org.junit.jupiter.params.provider.MethodSource;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertSame;
 
 import java.util.Collection;
 import java.util.List;
-
+import org.junit.jupiter.params.ParameterizedTest;
-import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.params.provider.MethodSource;
 
 /**
  * Date: 12/28/15 - 8:45 PM
+ *
  * @param <P> Prototype
  * @author Jeroen Meulemeester
  */
 public class PrototypeTest<P extends Prototype> {
   static Collection<Object[]> dataProvider() {
     return List.of(
-            new Object[]{new OrcBeast("axe"), "Orcish wolf attacks with axe"},
+        new Object[]{new OrcBeast("axe"), "Orcish wolf attacks with axe"},
-            new Object[]{new OrcMage("sword"), "Orcish mage attacks with sword"},
+        new Object[]{new OrcMage("sword"), "Orcish mage attacks with sword"},
-            new Object[]{new OrcWarlord("laser"), "Orcish warlord attacks with laser"},
+        new Object[]{new OrcWarlord("laser"), "Orcish warlord attacks with laser"},
-            new Object[]{new ElfBeast("cooking"), "Elven eagle helps in cooking"},
+        new Object[]{new ElfBeast("cooking"), "Elven eagle helps in cooking"},
-            new Object[]{new ElfMage("cleaning"), "Elven mage helps in cleaning"},
+        new Object[]{new ElfMage("cleaning"), "Elven mage helps in cleaning"},
-            new Object[]{new ElfWarlord("protecting"), "Elven warlord helps in protecting"}
+        new Object[]{new ElfWarlord("protecting"), "Elven warlord helps in protecting"}
     );
   }
 
   @ParameterizedTest
   @MethodSource("dataProvider")
-  public void testPrototype(P testedPrototype, String expectedToString) throws Exception {
+  public void testPrototype(P testedPrototype, String expectedToString) {
     assertEquals(expectedToString, testedPrototype.toString());
 
-    final Object clone = testedPrototype.copy();
+    final var clone = testedPrototype.copy();
     assertNotNull(clone);
     assertNotSame(clone, testedPrototype);
     assertSame(testedPrototype.getClass(), clone.getClass());

proxy/README.md

@@ -100,7 +100,7 @@ public class WizardTowerProxy implements WizardTower {
 And here is tower entering scenario
 
 ```java
-WizardTowerProxy proxy = new WizardTowerProxy(new IvoryTower());
+var proxy = new WizardTowerProxy(new IvoryTower());
 proxy.enter(new Wizard("Red wizard")); // Red wizard enters the tower.
 proxy.enter(new Wizard("White wizard")); // White wizard enters the tower.
 proxy.enter(new Wizard("Black wizard")); // Black wizard enters the tower.

proxy/src/main/java/com/iluwatar/proxy/App.java

@@ -44,7 +44,7 @@ public class App {
    */
   public static void main(String[] args) {
 
-    WizardTowerProxy proxy = new WizardTowerProxy(new IvoryTower());
+    var proxy = new WizardTowerProxy(new IvoryTower());
     proxy.enter(new Wizard("Red wizard"));
     proxy.enter(new Wizard("White wizard"));
     proxy.enter(new Wizard("Black wizard"));

proxy/src/test/java/com/iluwatar/proxy/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.proxy;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

proxy/src/test/java/com/iluwatar/proxy/IvoryTowerTest.java

@@ -23,14 +23,15 @@
 
 package com.iluwatar.proxy;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import com.iluwatar.proxy.utils.InMemoryAppender;
+import java.util.List;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 /**
  * Tests for {@link IvoryTower}
  */
@@ -49,18 +50,16 @@ public class IvoryTowerTest {
   }
 
   @Test
-  public void testEnter() throws Exception {
+  public void testEnter() {
-    final Wizard[] wizards = new Wizard[]{
+    final var wizards = List.of(
         new Wizard("Gandalf"),
         new Wizard("Dumbledore"),
         new Wizard("Oz"),
         new Wizard("Merlin")
-    };
+    );
 
-    IvoryTower tower = new IvoryTower();
+    var tower = new IvoryTower();
-    for (Wizard wizard : wizards) {
+    wizards.forEach(tower::enter);
-      tower.enter(wizard);
-    }
 
     assertTrue(appender.logContains("Gandalf enters the tower."));
     assertTrue(appender.logContains("Dumbledore enters the tower."));

proxy/src/test/java/com/iluwatar/proxy/WizardTest.java

@@ -23,20 +23,19 @@
 
 package com.iluwatar.proxy;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
 /**
  * Tests for {@link Wizard}
  */
 public class WizardTest {
 
   @Test
-  public void testToString() throws Exception {
+  public void testToString() {
-    final String[] wizardNames = {"Gandalf", "Dumbledore", "Oz", "Merlin"};
+    List.of("Gandalf", "Dumbledore", "Oz", "Merlin")
-    for (String name : wizardNames) {
+        .forEach(name -> assertEquals(name, new Wizard(name).toString()));
-      assertEquals(name, new Wizard(name).toString());
-    }
   }
 }

proxy/src/test/java/com/iluwatar/proxy/WizardTowerProxyTest.java

@@ -23,14 +23,15 @@
 
 package com.iluwatar.proxy;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import com.iluwatar.proxy.utils.InMemoryAppender;
+import java.util.List;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 /**
  * Tests for {@link WizardTowerProxy}
  */
@@ -50,17 +51,15 @@ public class WizardTowerProxyTest {
 
   @Test
   public void testEnter() throws Exception {
-    final Wizard[] wizards = new Wizard[]{
+    final var wizards = List.of(
         new Wizard("Gandalf"),
         new Wizard("Dumbledore"),
         new Wizard("Oz"),
         new Wizard("Merlin")
-    };
+    );
 
-    final WizardTowerProxy proxy = new WizardTowerProxy(new IvoryTower());
+    final var proxy = new WizardTowerProxy(new IvoryTower());
-    for (Wizard wizard : wizards) {
+    wizards.forEach(proxy::enter);
-      proxy.enter(wizard);
-    }
 
     assertTrue(appender.logContains("Gandalf enters the tower."));
     assertTrue(appender.logContains("Dumbledore enters the tower."));

proxy/src/test/java/com/iluwatar/proxy/utils/InMemoryAppender.java

@@ -26,10 +26,9 @@ package com.iluwatar.proxy.utils;
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.AppenderBase;
-import org.slf4j.LoggerFactory;
-
 import java.util.LinkedList;
 import java.util.List;
+import org.slf4j.LoggerFactory;
 
 
 /**
@@ -54,7 +53,7 @@ public class InMemoryAppender extends AppenderBase<ILoggingEvent> {
   }
 
   public boolean logContains(String message) {
-    return log.stream().anyMatch(event -> event.getFormattedMessage().equals(message));
+    return log.stream().map(ILoggingEvent::getFormattedMessage).anyMatch(message::equals);
   }
 
   public int getLogSize() {