# Unique Number in Java

In this post, we will develop a Java program to check whether the given number is a unique number or not.

A number that doesn’t have any duplicate digits is called a unique number. For example:- 123, 7158, 98547 are unique numbers, but 1111, 1233, 514425 are not unique numbers because they have one digit more than once.

For this task we need to use 2 loops (inner loop and outer loops). We have multiple ways to develop a Java method to check whether the given number is unique number or not.
1) By comparing each digits manually
2) Using Array
2) Using String

First, we will compare each digit manually. Procedure:-
1) Take a number
2) Find its last digit.
3) Compare all digits of the number with this last digit.
4) If it found more than one time then the number is not a unique number.
5) Else remove the last digit of the number
6) Repeat the 2 to 5 steps until the number becomes zero.

``````import java.util.Scanner;

public class UniqueNumber {

// method to check the Unique number
public static boolean isUnique(int number) {

int n1 = number; //1st temporary variable
int lastDigit = 0;
int n2; //2nd temporary variable
int count;

// iterate through all digits of number
while(n1 != 0) {

// find last digits
lastDigit = n1 % 10;

// compare this digit with
// all digits
n2 = number;
count = 0;

// loop
while(n2 != 0) {

// find last digit
// and compare
if(lastDigit == n2%10)
count++;

// remove last digit
n2 /= 10;
}

if(count != 1)
return false;

// remove last digit
n1 /= 10;
}

return true;
}

// main method
public static void main(String[] args) {

// declare variables
int number = 0;
boolean result = false;

//create Scanner class object to take input
Scanner scan = new Scanner(System.in);

// take input from end-user
System.out.print("Enter an integer number::");
number = scan.nextInt();

// check number is Unique number or not
result = isUnique(number);

// display
if(result)
System.out.println(number +
" is a Unique number.");
else
System.out.println(number +
" is not a Unique number.");

// close Scanner class object
scan.close();
}
}``````

The output for the different test-cases are:-

Enter an integer number::1234
1234 is a Unique number.

Enter an integer number::456845
456845 is not a Unique number.

## Check Unique number using Array

Now, We will develop the same program using an array. The idea is to find all digits of the number and store it in the array. Later compare values of all indexes with each other if they are the same the number is not a unique number.

But before comparing all indexes we need to declare an array of size “number_of_digits in the number”.

``````import java.util.Scanner;

public class UniqueNumberUsingArray {

// Method to check the Unique number
public static boolean isUnique(int number) {

// count number of digits
int digits = countDigits(number);

// declare array
int[] arr = new int[digits];

// initialize array
for(int i=0; i<digits; i++) {

// add last digit to ith position
arr[i] = (int)number%10;

// remove last digit
number /= 10;
}

// compare array elements
for(int i=0; i<digits; i++) {
for(int j=0; j<digits; j++) {
if(i!=j && arr[i]==arr[j])
return false;
}
}

return true;
}

public static int countDigits(int number) {
int count = 0;
while(number != 0) {
count++;
number /= 10;
}
return count;
}

// main method
public static void main(String[] args) {

// declare variables
int number = 0;
boolean result = false;

//create Scanner class object to take input
Scanner scan = new Scanner(System.in);

// take input from end-user
System.out.print("Enter an integer number::");
number = scan.nextInt();

// check number is Unique number or not
result = isUnique(number);

if(result)
System.out.println(number +
" is an Unique number.");
else
System.out.println(number +
" is not an Unique number.");

// close Scanner class object
scan.close();
}
}``````

## Using String

First, convert the given number into a String and then compare every character of the String with each other.

``````import java.util.Scanner;

public class UniqueNumberUsingString {

// Method to check the Unique number
private static boolean isUnique(int number) {

// convert number to string
String str = Integer.toString(number);

// compare characters of the String
for(int i=0; i<str.length(); i++) {
for(int j=0; j<str.length(); j++) {
if( i != j   &&
str.charAt(i)==str.charAt(j) )
return false;
}
}

return true;
}

// main method
public static void main(String[] args) {

// declare variables
int number = 0;
boolean result = false;

//create Scanner class object to take input
Scanner scan = new Scanner(System.in);

// take input from end-user
System.out.print("Enter an integer number::");
number = scan.nextInt();

// check number is Unique number or not
result = isUnique(number);

// display result
if(result)
System.out.println(number +
" is an Unique number.");
else
System.out.println(number +
" is not an Unique number.");

// close Scanner class object
scan.close();
}
}``````

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### 1 thought on “Unique Number in Java”

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