# Java Program to Check Unique Number

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 :

1. We ask the user to enter a number which we store in two integer variables.
2. We then use a while loop to iterate through all the digits in the number and check if they occur again.
3. 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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