Java 11 migrate c-d (remaining) (#1111)

* Moves converter pattern to Java 11

* Moves cqrs pattern to Java 11

* Moves dao pattern to Java 11

* Moves data-bus pattern to Java 11

* Moves data-locality pattern to Java 11

* Moves data-mapper pattern to Java 11

* Moves data-transfer-object pattern to Java 11

* Moves decorator pattern to Java 11

* Moves delegation pattern to Java 11

* Moves dependency-injection to Java 11

* Moves dirty-flag to Java 11

* Moves double-buffer to Java 11

* Moves double-checked-locking to Java 11

* Moves double-dispatch to Java 11

* Corrects with changes thats breaking test cases

dirty-flag/src/main/java/com/iluwatar/dirtyflag/App.java

@@ -23,9 +23,7 @@
 
 package com.iluwatar.dirtyflag;
 
-import java.util.List;
 import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -61,18 +59,15 @@ public class App {
    * Program execution point.
    */
   public void run() {
-
-    final ScheduledExecutorService executorService = Executors.newSingleThreadScheduledExecutor();
+    final var executorService = Executors.newSingleThreadScheduledExecutor();
     executorService.scheduleAtFixedRate(new Runnable() {
       final World world = new World();
 
       @Override
       public void run() {
-        List<String> countries = world.fetch();
+        var countries = world.fetch();
         LOGGER.info("Our world currently has the following countries:-");
-        for (String country : countries) {
-          LOGGER.info("\t" + country);
-        }
+        countries.stream().map(country -> "\t" + country).forEach(LOGGER::info);
       }
     }, 0, 15, TimeUnit.SECONDS); // Run at every 15 seconds.
   }
@@ -83,8 +78,7 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
-    App app = new App();
-
+    var app = new App();
     app.run();
   }
 

dirty-flag/src/main/java/com/iluwatar/dirtyflag/DataFetcher.java

@@ -27,8 +27,8 @@ import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -62,24 +62,18 @@ public class DataFetcher {
    * @return List of strings
    */
   public List<String> fetch() {
-    ClassLoader classLoader = getClass().getClassLoader();
-    File file = new File(classLoader.getResource(filename).getFile());
+    var classLoader = getClass().getClassLoader();
+    var file = new File(classLoader.getResource(filename).getFile());
 
     if (isDirty(file.lastModified())) {
       LOGGER.info(filename + " is dirty! Re-fetching file content...");
-
-      List<String> data = new ArrayList<String>();
-      try (BufferedReader br = new BufferedReader(new FileReader(file))) {
-        String line;
-        while ((line = br.readLine()) != null) {
-          data.add(line);
-        }
+      try (var br = new BufferedReader(new FileReader(file))) {
+        return br.lines().collect(Collectors.collectingAndThen(Collectors.toList(), List::copyOf));
       } catch (IOException e) {
         e.printStackTrace();
       }
-      return data;
     }
 
-    return new ArrayList<String>();
+    return List.of();
   }
 }

dirty-flag/src/main/java/com/iluwatar/dirtyflag/World.java

@@ -47,10 +47,8 @@ public class World {
    * @return List of strings
    */
   public List<String> fetch() {
-    List<String> data = df.fetch();
-
+    var data = df.fetch();
     countries = data.isEmpty() ? countries : data;
-
     return countries;
   }
 }

dirty-flag/src/test/java/org/dirty/flag/AppTest.java

@@ -23,19 +23,15 @@
 
 package org.dirty.flag;
 
-import java.io.IOException;
-
-import org.junit.jupiter.api.Test;
-
 import com.iluwatar.dirtyflag.App;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests that Dirty-Flag example runs without errors.
  */
 public class AppTest {
   @Test
-  public void test() throws IOException {
-    String[] args = {};
-    App.main(args);
+  public void test() {
+    App.main(new String[]{});
   }
 }

dirty-flag/src/test/java/org/dirty/flag/DirtyFlagTest.java

@@ -26,31 +26,26 @@ package org.dirty.flag;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import java.util.List;
-
+import com.iluwatar.dirtyflag.DataFetcher;
 import org.junit.jupiter.api.Test;
 
-import com.iluwatar.dirtyflag.DataFetcher;
-
 /**
- *
  * Application test
- *
  */
 public class DirtyFlagTest {
 
   @Test
   public void testIsDirty() {
-    DataFetcher df = new DataFetcher();
-    List<String> countries = df.fetch();
+    var df = new DataFetcher();
+    var countries = df.fetch();
     assertFalse(countries.isEmpty());
   }
 
   @Test
   public void testIsNotDirty() {
-    DataFetcher df = new DataFetcher();
+    var df = new DataFetcher();
     df.fetch();
-    List<String> countries = df.fetch();
+    var countries = df.fetch();
     assertTrue(countries.isEmpty());
   }
 }