java如何在不使用第三个变量的情况下交换两个数字？

Question

我见过很多在不使用第三个变量的情况下交换两个变量的技术。在不使用临时变量的情况下交换两个变量如何在不使用第三个变量的情况下交换两个数字？[重复]在不使用第三个变量的情况下交换2个变量的2个值

Answer 1

我将列出三种不同的技术，您可以使用它们来交换两个数字，而无需在Java中使用temp变量：

1. Swapping two numbers without using temp variable in Java

    int a = 10;
    int b = 20;
    
    System.out.println("value of a and b before swapping, a: " + a +" b: " + b);
    
    //swapping value of two numbers without using temp variable
    a = a+ b; //now a is 30 and b is 20
    b = a -b; //now a is 30 but b is 10 (original value of a)
    a = a -b; //now a is 20 and b is 10, numbers are swapped
    
    System.out.println("value of a and b after swapping, a: " + a +" b: " + b);

2. Swapping two numbers without using temp variable in Java with the bitwise operator

int a = 2; //0010 in binary
int b = 4; //0100 in binary
      
System.out.println("value of a and b before swapping, a: " + a +" b: " + b);
       
//swapping value of two numbers without using temp variable and XOR bitwise operator     
a = a^b; //now a is 6 and b is 4
b = a^b; //now a is 6 but b is 2 (original value of a)
a = a^b; //now a is 4 and b is 2, numbers are swapped
      
System.out.println("value of a and b after swapping using XOR bitwise operation, a: " + a +" b: " + b);

3. Swapping two numbers without using temp variable in Java with division and multiplication

    int a = 6;
    int b = 3;
    
    System.out.println("value of a and b before swapping, a: " + a +" b: " + b);
    
    //swapping value of two numbers without using temp variable using multiplication and division
    a = a*b; //now a is 18 and b is 3
    b = a/b; //now a is 18 but b is 6 (original value of a)
    a = a/b; //now a is 3 and b is 6, numbers are swapped
    
    System.out.println("value of a and b after swapping using multiplication and division, a: " + a +" b: " + b);

您还可以执行以下操作：

import java.util.Scanner;
 
public class Main {
 
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
 
    System.out.println("Enter x:");
    int x = scanner.nextInt();
 
    System.out.println("Enter y:");
    int y = scanner.nextInt();
 
    System.out.println("Before swap: x=" + x + ", y=" + y);
 
    x = x + y;
    y = x - y;
    x = x - y;
 
    System.out.println("After swap: x=" + x + ", y=" + y);
  }
}