Java Examples

Java - Swap two numbers



There are two common ways to swap the value of two variables:

  • Swap the value of two variables using a temporary variable
  • Swap the value of two variables without using temporary variable

Method 1: Swap the value of two variables using a temporary variable

In the example below, the initial value of variables x and y are 10 and 25. A temporary variable called temp is created to store the value of x and then the value of y is assigned to x. Finally, value of temp (which stores values of x) is assigned to variable y. The final value of variables x and y after swap are 25 and 10 respectively.

public class MyClass {
  static void swap(int x, int y) {
    System.out.println("Before Swap.");
    System.out.println("x = " + x);
    System.out.println("y = " + y);

    //Swap technique
    int temp = x;
    x = y;
    y = temp;

    System.out.println("After Swap.");
    System.out.println("x = " + x);
    System.out.println("y = " + y);
  }

  public static void main(String[] args) {
    swap(10, 25);
  }
}

The above code will give the following output:

Before Swap.
x = 10
y = 25
After Swap.
x = 25
y = 10

Method 2: Swap the value of two variables without using temporary variable

+ operator is used to swap the value of two variables. In this method no temporary variable is used. Please see the example below for syntax.

public class MyClass {
  static void swap(int x, int y) {
    System.out.println("Before Swap.");
    System.out.println("x = " + x);
    System.out.println("y = " + y);

    //Swap technique
    x = x + y;
    y = x - y;
    x = x - y;

    System.out.println("After Swap.");
    System.out.println("x = " + x);
    System.out.println("y = " + y);
  }

  public static void main(String[] args) {
    swap(10, 25);
  }
}

The above code will give the following output:

Before Swap.
x = 10
y = 25
After Swap.
x = 25
y = 10

Similarly, others operators can also be used in this method. Please see the page: Java - Swap two numbers without using Temporary Variable.




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