Basic type parameters are passed by address in Java implementation method

Keywords: Java

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Refer to some of the information on the Internet, and summarize it. You can go to the following bloggers for details

https://www.cnblogs.com/lixiaolun/p/4311863.html
http://blog.csdn.net/maoyeqiu/article/details/49250339

Here I find two ways to solve this problem:

The code of unchanged value is as follows:

package com.other.test;

public class Test {
    public static void change(int i, int j) { 
        int temp = i; 
        i = j; 
        j = temp;
    } 

    public static void main(String[] args) { 
        int a = 3; 
        int b = 4; 
        change(a, b); 
        System.out.println("a=" + a); 
        System.out.println("b=" + b);
    }
}

The output result is a=3 b=4, and the transferred value does not change the original value

Method 1: (array)

package com.other.test;

public class Test {
    public static void change(int[] counts) { 
        counts[0] = 6; 
        System.out.println(counts[0]);
    } 

    public static void main(String[] args) { 
        int[] count = { 1, 2, 3, 4, 5 }; 
        change(count);
        System.out.println(count[0]);
    } 
}

The output is 6 6, which means the referenced value changes the original value

Method 2: (object)

package Test;

import java.util.Scanner;

class dataWrap
{
    int a;
    int b;
}
public class lsk{

        public static void swap(dataWrap dw)
        {
            int tmp=dw.a;
            dw.a=dw.b;
            dw.b=tmp;
            System.out.println("swap Method, the value of the member variable is"+dw.a+":b The value of the member variable is"+dw.b);
        }

        public static void main(String[] args)
        {
            dataWrap dw=new dataWrap();
            dw.a=6;
            dw.b=9;
            swap(dw);
            System.out.println("After transformation, a The value of the member variable is"+dw.a+":b The value of the member variable is:"+dw.b);
        }
}

The operation result is:
In the swap method, the value of the member variable is 9:b the value of the member variable is 6
After transformation, the value of a member variable is 9:b member variable is 6

Method 2: Object-based can also be implemented in this way:

public class Test {

private static Integer a;
private static Integer b;

public void setA(Integer a) {
this.a = a;
}

public void setB(Integer b) {
this.b = b;
}

/* Exchange the values of two parameters in this method */
public void swap(Integer a, Integer b) {
setA(b);
setB(a);
}

public static void main(String[] args) {
a = new Integer(10);
b = new Integer(5);
System.out.println("a=" + a + "\tb=" + b);
new Test().swap(a, b);
System.out.println("a=" + a + "\tb=" + b);
}

}

Posted by centered effect on Tue, 05 May 2020 17:19:27 -0700