Lambda语法格式

package com.atguigu.java8;
import org.testng.annotations.Test;

import java.util.*;
import java.util.function.Consumer;



public class TestLambda2 {

    // 语法格式一：无参数，无返回值
    @Test
    public void test1(){
        Runnable r = new Runnable() {
            @Override
            public void run() {
                System.out.println("Hello world!");
            }
        };
        r.run();
        System.out.println("------------------");
        Runnable r1 = () -> System.out.println("Hello Lambda!");
        r1.run();
    }

    // 语法格式二：有一个参数，无返回值
    @Test
    public void test2(){
        Consumer con = (x) -> System.out.println(x);
        con.accept("ababababa");
    }

    // 语法格式三；有多个参数，并且有返回值，有多条语句，必须使用大括号
    @Test
    public void test3(){
        Comparator com = (x, y) -> {
            System.out.println("Hello world!");
            return Integer.compare(x,y);
        };
        com.compare(12,232);
        System.out.println(com);
    }

    // 语法格式四；多个参数，只有一个返回语句，大括号和return可以省略
    @Test
    public void test4(){
        Comparator com = (x, y) -> Integer.compare(x,y);
    }

    @Test
    public void test5(){
        String[] str = {"s","f"};
        String[] str1 = {"a","d"};
        List list = new ArrayList<>();
        show(new HashMap<>());
    }
    public void show(Map mp){
    }

    // 利用Lambda表达式实现前提需要函数接口，实现了重复利用
    @Test
    public void test6(){
        Integer num = operation(100, (x) -> x * x);
        System.out.println(num);

        Integer num2 = operation(200, (x) -> x + 200);
        System.out.println(num2);
    }
    public Integer operation(Integer num, MyFun mf){
        return mf.getValue(num);
    }
}