Lambda expression

Why is there Lambda expression ？

Java Support Lambda Expression starts with Java 8, Its appearance simplifies the syntax of anonymous inner classes of functional interfaces

How do you use it? ？

1.

The expression syntax is as follows ：([ Parameters 1], [ Parameters 2], [ Parameters 3],… [ Parameters n])->{ Code block }
example ：
Look at the following main The content of the method ：

// Anonymous inner class ：
@FunctionalInterface
interface IComputer {
    	
	void add(int a, int b);
}
public class Test {
    
	public static void main(String[] args) {
    
		IComputer computer = new IComputer() {
    		
			@Override
			public void add(int a, int b) {
    
				System.out.println(a + b);
			}
		};
		computer.add(1, 1);
	}
}
//Lambda  expression ：
@FunctionalInterface
interface IComputer {
    	
	void add(int a, int b);
}
public class Test {
    
	public static void main(String[] args) {
    
		IComputer computer = (int a, int b)-> {
    
			System.out.println(a + b);
		};	
		computer.add(1, 1);
	}
}

2.

If the method has no return value and only one line of code , be Lambda Expression syntax can be in this form ：([ Parameters 1], [ Parameters 2], [ Parameters 3],… [ Parameters n])-> Single line statement , Here's an example ：

// Anonymous inner class ：
@FunctionalInterface
interface IMammal {
    
	void move(String name);
	}
public class Test {
    
	public static void main(String[] args) {
    
		IMammal whale = (name) -> {
    
			System.out.println(name+" Moving ......");
		};
		whale.move(" Whale ");
	}
}
//Lambda  expression ：
@FunctionalInterface
interface IMammal {
    
	void move(String name);
}
public class Test {
    
	public static void main(String[] args) {
    
		IMammal whale = (name) -> System.out.println(name+" Moving ......");
		whale.move(" Whale ");
	}
}

3.

If the method has a return value and only one line of code , be Lambda Expression syntax can be in this form ：([ Parameters 1], [ Parameters 2], [ Parameters 3],… [ Parameters n])-> expression , Here's an example ：

// Anonymous inner class ：
@FunctionalInterface
interface IComputer {
	int add(int a, int b);
}
public class Test {
	public static void main(String[] args) {
		IComputer computer = (a, b) -> {
			return a+b;
		};
		int result = computer.add(1,2);
		System.out.println(result);
	}
}
//Lambda  expression ：
@FunctionalInterface
interface IComputer {
	int add(int a, int b);
}
public class Test {
	public static void main(String[] args) {
		IComputer computer = (a, b) -> a+b;
		int result = computer.add(1,2);
		System.out.println(result);
	}
}