w3resource
Java Programming Exercies

Java Exercises: Find a number that appears only once in a given array of integers, all numbers occur twice

Java Basic: Exercise-129 with Solution

Write a Java program to find a number that appears only once in a given array of integers, all numbers occur twice.
Example: {10,2,38,23,38,23,21}
Output: 23

Pictorial Presentation:

Java Basic Exercises: Find a number that appears only once  in a given array of integers, all numbers occur twice.

Sample Solution:

Java Code:

import java.util.*;
public class Main {
  public static  void main(String[] arg) 
   {
	 int nums[] = {10, 20, 10, 20, 30, 40, 40, 30, 50};
	 int result;
	 System.out.println("Source Array : "+Arrays.toString(nums));   
     result = getSingleNumber(nums);
     System.out.println("\n"+result+" appears only once.");
    }

     public static int getSingleNumber(int[] nums) {
       if(nums == null || nums.length == 0) {
         return -1;
        }
        int result = 0;
        for (int i = 0; i < nums.length; i++) {
            result ^= nums[i];
        }
        return result;
    }
}

Sample Output:

Source Array : [10, 20, 10, 20, 30, 40, 40, 30, 50]

50 appears only once  

Flowchart:

Flowchart: Java exercises: Find a number that appears only once  in a given array of integers, all numbers occur twice.

Java Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a Java program to get the Postorder traversal of its nodes' values of a given a binary tree.
Next: Write a Java program to find the maximum depth of a given a binary tree

What is the difficulty level of this exercise?