2021-04-16 method overload parameter transfer

Method overloading

Overloading is in a class , Have the same function name , But functions with different parameters
Method overload rules ：

1. The method name must be the same
2. Parameter list must be different （ The number is different. , Or of different types , Different parameter sorting lists, etc ）
3. Methods can have the same or different return types
4. It's not enough to be an overload of a method just because the return type is different

public class Demo3 {
    
    public static void main(String[]args){
    
        int max = max(10,20,30);
        System.out.println(max);
    }
    // Than the size 
    public static int max(double num1,double num2){
    
        return 0;
    }
    // Than the size 
    public static int max(int num1,int num2){
    
        return  0;
    }
    // Than the size 
    public static int max(int num1,int num2,int num3){
    
        return 0;
    }
}

Command line arguments

Sometimes I want to give him a message when I run a program , This depends on passing command line arguments to main（） Function implementation

Variable parameters

Java Support passing variable parameters of the same type to a method
In the method declaration , Add an ellipsis after the specified parameter type
Only one variable parameter can be specified in a method , It must be the last parameter of the method , Any ordinary parameter must be declared before it

public class Demo4 {
    
    public static void main(String[]args){
    
        Demo4 demo4 = new Demo4();
        demo4.test(1);
    }
    public void test (int...i){
    
        System.out.println(i[0]);
    }
}