#36 rxjava: functional descriptor

RxJava/practice/src/main/java/org/example/ex06/FunctionalDescriptorConsumer.java

@@ -0,0 +1,20 @@
+package org.example.ex06;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Consumer;
+
+/**
+ * 함수 디스크립터의 Consumer 예제
+ */
+public class  FunctionalDescriptorConsumer {
+    public static void main(String[] args) {
+        List<Integer> numbers = Arrays.asList(1, 6, 10, 30, 65, 70, 102);
+        forEachPrint(numbers, n -> System.out.println(n));
+    }
+
+    public static <T> void forEachPrint(List<T> numbers, Consumer<T> c) {
+        for(T number : numbers)
+            c.accept(number);
+    }
+}

RxJava/practice/src/main/java/org/example/ex06/FunctionalDescriptorFunction.java

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+package org.example.ex06;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Function;
+
+/**
+ * 함수 디스크립터의 Function 예제
+ */
+public class FunctionalDescriptorFunction {
+    public static void main(String[] args) {
+        List<Character> characterList = Arrays.asList('a', 'b', 'c', 'd', 'e');
+        List<Integer> asciiNumbers = map(characterList, character -> (int) character);
+
+        for(int asciiNumber : asciiNumbers)
+            System.out.println(asciiNumber);
+    }
+
+    public static <T, R> List<R> map(List<T> list, Function<T, R> f){
+        List<R> result = new ArrayList<>();
+        for(T t : list)
+            result.add(f.apply(t));
+        return result;
+    }
+}

RxJava/practice/src/main/java/org/example/ex06/FunctionalDescriptorPredicate.java

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+package org.example.ex06;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Predicate;
+
+/**
+ * 함수 디스크립터의 Predicate 예제
+ */
+public class FunctionalDescriptorPredicate {
+    public static void main(String[] args) {
+        List<Integer> numbers = Arrays.asList(1, 6, 10, 30, 65, 70, 102);
+        List<Integer> result = filter(numbers, n -> n > 30);
+
+        for(int number : result)
+            System.out.println(number);
+    }
+
+    private static <T> List<T> filter(List<T> numbers, Predicate<T> p){
+        List<T> result = new ArrayList<>();
+        for(T number : numbers)
+            if(p.test(number))
+                result.add(number);
+
+        return result;
+    }
+}