Several simplified forms of lambda expression

For a functional interface （ There is only one method interface ）, We can use lambda Expression to realize its , Here's how to use lambda Several simplified forms of expression

1. Conventional form （ There are parameter types , There are brackets , There are curly braces. ）

public class lamda {
    

    public static void main(String[] args) {
    
        Hello like = (int i)->{
    
            System.out.println("hello" + i);
        };
        like.hello(5);
    }
}
interface Hello {
    
     void hello(int i);
}

2. Simplified parameter type

For methods that have no parameters or one parameter ：

Can be simplified

public class lamda {
    

    public static void main(String[] args) {
    
        Hello like = (i)->{
    
            System.out.println("hello" + i);
        };
        like.hello(5);
    }
}
interface Hello {
    
     void hello(int i);
}

For methods with multiple parameters ：

To simplify , All simplified

public class lamda {
    

    public static void main(String[] args) {
    

        Hello like = (i,j)->{
    
            System.out.println("hello" + i + j);
        };

        like.hello(5,"world");
    }
}
interface Hello {
    
     void hello(int i,String j);
}

3. Simplified brackets

For methods that have no parameters or one parameter ：

Can be simplified

public class lamda {
    

    public static void main(String[] args) {
    

        Hello like = i->{
    
            System.out.println("hello" + i);
        };

        like.hello(5,);
    }
}
interface Hello {
    
     void hello(int i);
}

For methods with multiple parameters ：

Irreducible parentheses

4. Simplify curly braces

For methods with only one line of code ：

Can be simplified

public class lamda {
    
    public static void main(String[] args) {
    
        Hello like = (i,j)->System.out.println("hello" + i + j);
        like.hello(5,"world");
    }
}
interface Hello {
    
     void hello(int i,String j);
}

For methods with multiple lines of code ：

Do not simplify curly braces

summary ：

• The premise is that the interface is functional （ There is only one method interface ）
• All the above simplified forms can be used together , That is, the parameter type can be simplified , You can also simplify parentheses
• lambda An expression can only be simplified to one line if it has only one line of code , If there are many lines , Then wrap it in code blocks .
• Multiple parameters can also be swept parameter types , If you want to get rid of everything , It has to be bracketed