Java 11 migraiton: monad

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

@@ -41,9 +41,8 @@ import org.slf4j.LoggerFactory;
  * instance of a plain object with {@link Validator#of(Object)} and validates it {@link
  * Validator#validate(Function, Predicate, String)} against given predicates.
  *
- * <p>As a validation result {@link Validator#get()} it either returns valid object {@link
- * Validator#t} or throws a list of exceptions {@link Validator#exceptions} collected during
- * validation.
+ * <p>As a validation result {@link Validator#get()} either returns valid object
+ * or throws {@link IllegalStateException} with list of exceptions collected during validation.
  */
 public class App {
 
@@ -55,10 +54,10 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
-    User user = new User("user", 24, Sex.FEMALE, "foobar.com");
+    var user = new User("user", 24, Sex.FEMALE, "foobar.com");
     LOGGER.info(Validator.of(user).validate(User::getName, Objects::nonNull, "name is null")
         .validate(User::getName, name -> !name.isEmpty(), "name is empty")
-        .validate(User::getEmail, email -> !email.contains("@"), "email doesn't containt '@'")
+        .validate(User::getEmail, email -> !email.contains("@"), "email doesn't contains '@'")
         .validate(User::getAge, age -> age > 20 && age < 30, "age isn't between...").get()
         .toString());
   }

monad/src/main/java/com/iluwatar/monad/User.java

@@ -28,10 +28,10 @@ package com.iluwatar.monad;
  */
 public class User {
 
-  private String name;
-  private int age;
-  private Sex sex;
-  private String email;
+  private final String name;
+  private final int age;
+  private final Sex sex;
+  private final String email;
 
   /**
    * Constructor.

monad/src/main/java/com/iluwatar/monad/Validator.java

@@ -85,18 +85,21 @@ public class Validator<T> {
   }
 
   /**
-   * Extension for the {@link Validator#validate(Function, Predicate, String)} method, dedicated for
-   * objects, that need to be projected before requested validation.
+   * Extension for the {@link Validator#validate(Predicate, String)} method, dedicated for objects,
+   * that need to be projected before requested validation.
    *
    * @param projection function that gets an objects, and returns projection representing element to
    *                   be validated.
-   * @param validation see {@link Validator#validate(Function, Predicate, String)}
-   * @param message    see {@link Validator#validate(Function, Predicate, String)}
-   * @param <U>        see {@link Validator#validate(Function, Predicate, String)}
+   * @param validation see {@link Validator#validate(Predicate, String)}
+   * @param message    see {@link Validator#validate(Predicate, String)}
+   * @param <U>        see {@link Validator#validate(Predicate, String)}
    * @return this
    */
-  public <U> Validator<T> validate(Function<T, U> projection, Predicate<U> validation,
-                                   String message) {
+  public <U> Validator<T> validate(
+      Function<T, U> projection,
+      Predicate<U> validation,
+      String message
+  ) {
     return validate(projection.andThen(validation::test)::apply, message);
   }
 
@@ -110,7 +113,7 @@ public class Validator<T> {
     if (exceptions.isEmpty()) {
       return obj;
     }
-    IllegalStateException e = new IllegalStateException();
+    var e = new IllegalStateException();
     exceptions.forEach(e::addSuppressed);
     throw e;
   }

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

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

monad/src/test/java/com/iluwatar/monad/MonadTest.java

@@ -23,13 +23,12 @@
 
 package com.iluwatar.monad;
 
-import org.junit.jupiter.api.Test;
-
-import java.util.Objects;
-
 import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
+import java.util.Objects;
+import org.junit.jupiter.api.Test;
+
 /**
  * Test for Monad Pattern
  */
@@ -37,27 +36,33 @@ public class MonadTest {
 
   @Test
   public void testForInvalidName() {
-    User tom = new User(null, 21, Sex.MALE, "tom@foo.bar");
-    assertThrows(IllegalStateException.class, () -> {
-      Validator.of(tom).validate(User::getName, Objects::nonNull, "name cannot be null").get();
-    });
+    var tom = new User(null, 21, Sex.MALE, "tom@foo.bar");
+    assertThrows(
+        IllegalStateException.class,
+        () -> Validator.of(tom)
+            .validate(User::getName, Objects::nonNull, "name cannot be null")
+            .get()
+    );
   }
 
   @Test
   public void testForInvalidAge() {
-    User john = new User("John", 17, Sex.MALE, "john@qwe.bar");
-    assertThrows(IllegalStateException.class, () -> {
-      Validator.of(john).validate(User::getName, Objects::nonNull, "name cannot be null")
-              .validate(User::getAge, age -> age > 21, "user is underaged")
-              .get();
-    });
+    var john = new User("John", 17, Sex.MALE, "john@qwe.bar");
+    assertThrows(
+        IllegalStateException.class,
+        () -> Validator.of(john)
+            .validate(User::getName, Objects::nonNull, "name cannot be null")
+            .validate(User::getAge, age -> age > 21, "user is underage")
+            .get()
+    );
   }
 
   @Test
   public void testForValid() {
-    User sarah = new User("Sarah", 42, Sex.FEMALE, "sarah@det.org");
-    User validated = Validator.of(sarah).validate(User::getName, Objects::nonNull, "name cannot be null")
-        .validate(User::getAge, age -> age > 21, "user is underaged")
+    var sarah = new User("Sarah", 42, Sex.FEMALE, "sarah@det.org");
+    var validated = Validator.of(sarah)
+        .validate(User::getName, Objects::nonNull, "name cannot be null")
+        .validate(User::getAge, age -> age > 21, "user is underage")
         .validate(User::getSex, sex -> sex == Sex.FEMALE, "user is not female")
         .validate(User::getEmail, email -> email.contains("@"), "email does not contain @ sign")
         .get();