JDK1.8_lambda expression

Create thread

        new Thread(new Runnable() {
    
    
            @Override
            public void run() {
    
    
                System.out.println("我是一个线程哦");
            }
        }).start();
        

lambda creates thread

  new Thread(() -> System.out.println("我是一个线程哦")).start();

Lambda implements abstract methods

Precautions:

1. There is one and only one abstract method in the implementation interface of lambda; the
   context must be available to derive the interface corresponding to the lambda.

public interface Eat {
    
    
    int eat(int a,int b);
}

Omission method:

1. The parameter type can be omitted. In the case of multiple parameters, only one cannot be omitted;
2. When there is only one parameter, the parentheses can be omitted;
3. When there is only one method body or code block, braces, semicolons, and return can all be omitted.

Define a method, pass the formal parameters into the interface, the method body rewrites the method of the interface, and then the main method calls the lambda style

        TestEat((int a, int b) -> {
    
    
            return a + b;
        });
    }
    //----------省略过后-----------------
           TestEat((a, b) ->
                a + b
        );
    //-----------------------------------
    public static void TestEat(Eat e) {
    
    
        int i = e.eat(10, 20);
        System.out.println(i);//30
    }

The difference between lambda and anonymous inner class

// 接口中有两个方法,直接报错
        TestEat((a, b) ->
                a + b   
        );
// 接口中有两个方法,匿名内部类可以使用
        TestEat(new Eat() {
    
    
            @Override
            public int eat(int a, int b) {
    
    
               return a+b;
            }

            @Override
            public void method() {
    
    
                System.out.println("匿名内部类新增的方法");
            }
        });
    }
    //-----------------------------------
    public static void TestEat(Eat e) {
    
    
        int i = e.eat(10, 20);
        System.out.println(i);
    }
}