Aggiunto modulo per esempi del libro "Modern Java in Action"

modern-java/src/main/java/org/gym/fp/moderjava/Dish.java

@@ -0,0 +1,26 @@
+package org.gym.fp.moderjava;
+
+import lombok.AllArgsConstructor;
+import lombok.Value;
+
+@Value
+@AllArgsConstructor
+public final class Dish {
+    private final String name;
+    private final int calories;
+    private final Type type;
+
+    public enum Type {
+        MEAT, FISH, VEGETARIAN, OTHER
+    }
+
+    public boolean isVegetarian() {
+        return this.type == Type.VEGETARIAN;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+
+}

modern-java/src/main/java/org/gym/fp/moderjava/StreamTest.java

@@ -0,0 +1,78 @@
+package org.gym.fp.moderjava;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static java.lang.System.out;
+
+public class StreamTest {
+
+    public static void main(String[] args) {
+        doStreamFilterDemo();
+        doStreamMappingDemo();
+    }
+
+    private static void doStreamFilterDemo() {
+        out.println("FILTER EXAMPLE");
+        getDishes().stream()
+                   .filter(Dish::isVegetarian)
+                   .collect(Collectors.toList())
+                   .forEach(out::println);
+        out.println("----------------------------------------");
+        out.println("DISTINCT EXAMPLE");
+        getDishes().stream()
+                   .filter(dish -> dish.getName().length() > 4)
+                   .distinct()
+                   .forEach(out::println);
+        out.println("----------------------------------------");
+        out.println("TAKEWHILE EXAMPLE");
+        getDishes().stream()
+                   .takeWhile(dish -> dish.getCalories() > 40)
+                   .forEach(out::println);
+        out.println("----------------------------------------");
+        out.println("DROPWHILE EXAMPLE");
+        getDishes().stream()
+                   .dropWhile(dish -> dish.getCalories() > 40)
+                   .forEach(out::println);
+        out.println("----------------------------------------");
+    }
+
+    private static void doStreamMappingDemo() {
+        List<String> words = Arrays.asList("Hello", "World");
+        List<String> uniqueCharacters = words.stream()
+                                             .map(word -> word.split(""))
+                                             .flatMap(Arrays::stream)
+                                             .distinct()
+                                             .collect(Collectors.toList());
+        out.println(uniqueCharacters);
+        out.println("----------------------------------------");
+        List<Integer> numbers1 = Arrays.asList(1, 2, 3);
+        List<Integer> numbers2 = Arrays.asList(3, 4);
+        List<int[]> pairs1 = numbers1.stream()
+                                     .flatMap(i -> numbers2.stream().map(j -> new int[]{i, j}))
+                                     .collect(Collectors.toList());
+        pairs1.forEach(pair -> out.println(Arrays.toString(pair)));
+        out.println("----------------------------------------");
+        List<int[]> pairs2 = numbers1.stream()
+                                     .flatMap(i -> numbers2.stream().map(j -> new int[]{i, j}))
+                                     .filter(pair -> (pair[0] + pair[1]) % 3 == 0)
+                                     .collect(Collectors.toList());
+        pairs2.forEach(pair -> out.println(Arrays.toString(pair)));
+    }
+
+    private static List<Dish> getDishes() {
+        List<Dish> dishes = Arrays.asList(
+                new Dish("pork", 300, Dish.Type.MEAT),
+                new Dish("salad", 50, Dish.Type.VEGETARIAN),
+                new Dish("chicken", 100, Dish.Type.MEAT),
+                new Dish("chicken", 100, Dish.Type.MEAT),
+                new Dish("tomato", 30, Dish.Type.VEGETARIAN),
+                new Dish("tunny", 120, Dish.Type.FISH),
+                new Dish("potato", 70, Dish.Type.VEGETARIAN)
+                                         );
+        return Collections.unmodifiableList(dishes);
+    }
+
+}