In the previous article, we have discussed Java Program to find Reverse Number of a Given Number

In this article we are going to understand what Unique number is and how we can check whether a number is Unique or not in Java with examples.

## Program to Check Unique Number

**Unique numbers** are numbers where the digits are not repeated i.e. number formed without repetition of any digits.

Example: 236: 236 is Unique Number 121: 121 is not Unique Number 54: 54 is Unique number

In the above examples the numbers 236 and 54 are unique numbers. 121 has 1 repeated in it so it it not an unique number.

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**Approach :**

- We ask the user to enter a number which we store in two integer variables.
- We then use a while loop to iterate through all the digits in the number and check if they occur again.
- If the occurrence of any number is more than 1 it is not an unique number, else it is.

Let’s see different ways to check unique number.

### Method-1: Java Program to Check Unique Number By Using Static Value

import java.util.Scanner; public class UniqueNumber{ public static void main(String args[]) { //A number declared int num = 78; //n1 and n2 are variable holders for num, counter is the digit counter int n1 = num, n2 = num, remainder1, remainder2, counter=0; //Checking the occurence of digits while (n1 > 0) { remainder1 = n1 % 10; while (n2 > 0) { remainder2 = n2 % 10; if (remainder1 == remainder2) { counter++; } n2 = n2 / 10; } n1 = n1 / 10; } if(counter==1) { System.out.println(num+" is an unique number"); } else { System.out.println(num+" is not an unique number"); } } }

Output: 78 is an unique number

### Java Program to Check Unique Number By User Input Value

import java.util.Scanner; public class UniqueNumber{ public static void main(String args[]) { //Taking the number as input from the user using scanner class Scanner scan = new Scanner(System.in); System.out.print("Enter a number : "); int num = scan.nextInt(); //n1 and n2 are variable holders for num, counter is the digit counter int n1 = num, n2 = num, remainder1, remainder2, counter=0; //Checking the occurence of digits while (n1 > 0) { remainder1 = n1 % 10; while (n2 > 0) { remainder2 = n2 % 10; if (remainder1 == remainder2) { counter++; } n2 = n2 / 10; } n1 = n1 / 10; } if(counter==1) { System.out.println(num+" is an unique number"); } else { System.out.println(num+" is not an unique number"); } } }

Output: Case-1 Enter a number : 56 56 is an unique number Case-2 Enter a number : 111 111 is not an unique number

### Method-3: Java Program to Check Unique Number By Using User Defined Method

import java.util.Scanner; public class UniqueNumber{ public static void main(String args[]) { //Taking the number as input from the user using scanner class Scanner scan = new Scanner(System.in); System.out.print("Enter a number : "); int num = scan.nextInt(); //calling the user defined method //to check unique number or not. checkNumber(num); } //checkNumber() method to check unique number public static void checkNumber(int num) { //n1 and n2 are variable holders for num, counter is the digit counter int n1 = num, n2 = num, remainder1, remainder2, counter=0; //Checking the occurence of digits while (n1 > 0) { remainder1 = n1 % 10; while (n2 > 0) { remainder2 = n2 % 10; if (remainder1 == remainder2) { counter++; } n2 = n2 / 10; } n1 = n1 / 10; } if(counter==1) { System.out.println(num+" is an unique number"); } else { System.out.println(num+" is not an unique number"); } } }

Output: Case-1 Enter a number : 56 56 is an unique number Case-2 Enter a number : 111 111 is not an unique number

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