rxjava : lambda

RxJava/basic/src/_01_lambda/LambdaEx_03.java

@@ -0,0 +1,46 @@
+package _01_lambda;
+
+public class LambdaEx_03 {
+
+    @FunctionalInterface
+    interface MyFunction1 {
+        int calc(int a);
+    }
+
+    @FunctionalInterface
+    interface MyFunction2 {
+        int calc(int a, int b);
+    }
+
+    @FunctionalInterface
+    interface MyFunction3 {
+        void print();
+    }
+
+    public static void main(String[] args) {
+
+        // 파라미터가 1개인 람다식
+        MyFunction1 result1 = (x) -> { return x + x; };
+        MyFunction1 result2 = x -> x + x; // 괄호 생략 가능
+        System.out.println("result1 = " + result1.calc(5));
+        System.out.println("result2 = " + result2.calc(5));
+
+        // 파라미터가 2개인 람다식
+        MyFunction2 add = (x, y) -> x + y;
+        MyFunction2 minus = (x, y) -> x - y;
+        System.out.println("add = " + add.calc(1, 2));
+        System.out.println("minus = " + minus.calc(1, 2));
+
+        // 파라미터가 없는 람다식
+        MyFunction3 myFunction3 = () -> System.out.println("print method");
+        myFunction3.print();
+
+        // 함수형 인터페이스 파라미터로 전달
+        printSum(3, 4, (x, y) -> x * y);
+
+    }
+
+    static void printSum(int x, int y, MyFunction2 f) {
+        System.out.println(f.calc(x, y));
+    }
+}