» » Swap two numbers without using third variable

1. Java Interview Program to Swap two numbers without using third variable in java



  1. package com.instaceofjava;
  2.  
  3. public class SwapTwoNumbers {
  4.  
  5. public static void main(String[] args) {
  6.  
  7. int number1=20;
  8. int number2=30;
  9.  
  10. System.out.println("Before Swapping");
  11. System.out.println("Value of number1 is :" + number1);
  12. System.out.println("Value of number2 is :" +number2); 
  13.  
  14. number1=number1+number2;
  15. number2=number1-number2;
  16. number1=number1-number2;
  17.  
  18. System.out.println("After Swapping");
  19. System.out.println("Value of number1 is :" + number1);
  20. System.out.println("Value of number2 is :" +number2);
  21.  
  22. }
  23. }
Output:

  1. Before Swapping
  2. Value of number1 is :20
  3. Value of number2 is :30
  4. After Swapping
  5. Value of number1 is :30
  6. Value of number2 is :20

2. Java Program to Swap two numbers by using division and multiplication.


  1. package com.instaceofjava;
  2.  
  3. public class SwapTwoNumbers {
  4.  
  5. public static void main(String[] args) {
  6.  
  7. int number1=20;
  8. int number2=30;
  9.  
  10. System.out.println("Before Swapping");
  11. System.out.println("Value of number1 is :" + number1);
  12. System.out.println("Value of number2 is :" +number2); 
  13.  
  14. number1=number1*number2;
  15. number2=number1/number2;
  16. number1=number1/number2;
  17.  
  18. System.out.println("After Swapping");
  19. System.out.println("Value of number1 is :" + number1);
  20. System.out.println("Value of number2 is :" +number2);
  21.  
  22. }
  23. }


Output:

  1. Before Swapping
  2. Value of number1 is :20
  3. Value of number2 is :30
  4. After Swapping
  5. Value of number1 is :30
  6. Value of number2 is :20


3. Java Program to Swap two integers by using bit wise operators


  1. package com.instaceofjava;
  2.  
  3. public class SwapTwoNumbers {
  4.  
  5. public static void main(String[] args) {
  6.  
  7. int number1=2;
  8. int number2=4;
  9.  
  10. System.out.println("Before Swapping");
  11. System.out.println("Value of number1 is :" + number1);
  12. System.out.println("Value of number2 is :" +number2); 
  13.  
  14. number1=number1^number2;
  15. number2=number1^number2;
  16. number1=number1^number2;
  17.  
  18. System.out.println("After Swapping");
  19. System.out.println("Value of number1 is :" + number1);
  20. System.out.println("Value of number2 is :" +number2);
  21.  
  22. }
  23. }
Output:

  1. Before Swapping
  2. Value of number1 is :2
  3. Value of number2 is :4
  4. After Swapping
  5. Value of number1 is :4
  6. Value of number2 is :2


Instance Of Java

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3 comments for Swap two numbers without using third variable

  1. 1) and 2) doesn't work for all valid integers.
    Take for 1) the following numbers: 1 and Integer.MAX_VALUE
    Take for 2) the following numbers: any integer and 0
    3) Could work

    ReplyDelete
    Replies
    1. The first method is working fine with large values.
      I have tested with Integer.MAX_VALUE-20 and Integer.MAX_VALUE using JRE 1.8.0

      Calculation :
      x = x + y
      = 2147483627 + 2147483647
      = -22

      y = x - y
      = -22 - 2147483647
      = 2147483627 (don't know how JVM calculated this)

      x = x - y
      = -22 - 2147483627
      = 2147483647 (don't know how JVM calculated this)

      I am trying to figure out how JVM calculates it. If someone knows the calculation logic. Please explain.

      Delete

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