Java: Validate a personal identification number (PIN)

Last update on May 24 2025 12:58:58 (UTC/GMT +8 hours)

18. Validate PIN Code

(PIN): A personal identification number, or PIN, is a string of at least four digits used to unlock a bank account or card to which it has been assigned.

Write a Java program to validate a personal identification number (PIN). Assume a PIN number is 4, 6 or 8.

Sample Solution-1:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	    String n = "123";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));
	    n = "1234";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));
	    n = "12345";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));	
	    n = "123456";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));
	    n = "1234567";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));	    
		n = "12345678";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));
		n = "123456789";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));		
        }

   public static boolean validate(String n) {
	   return n.matches("\\d{4}|\\d{6}|\\d{8}");
   }
}

Sample Output:

Original PIN Number: 123
Is the said PIN number is valid? false
Original PIN Number: 1234
Is the said PIN number is valid? true
Original PIN Number: 12345
Is the said PIN number is valid? false
Original PIN Number: 123456
Is the said PIN number is valid? true
Original PIN Number: 1234567
Is the said PIN number is valid? false
Original PIN Number: 12345678
Is the said PIN number is valid? true
Original PIN Number: 123456789
Is the said PIN number is valid? false

Pictorial Presentation:

Flowchart :

Sample Solution-2:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	    String n = "123";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));
	    n = "1234";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));
	    n = "12345";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));	
	    n = "123456";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));
	    n = "1234567";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));	    
		n = "12345678";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));
		n = "123456789";
		System.out.println("Original PIN Number: "+n);
		System.out.println("Is the said PIN number is valid? "+validate(n));		
        }

   public static boolean validate(String n) {
	   return n.matches("[0-9]+") && n.length() == 4 || n.length() == 6 || n.length() == 8;
   }
}

Sample Output:

Original PIN Number: 123
Is the said PIN number is valid? false
Original PIN Number: 1234
Is the said PIN number is valid? true
Original PIN Number: 12345
Is the said PIN number is valid? false
Original PIN Number: 123456
Is the said PIN number is valid? true
Original PIN Number: 1234567
Is the said PIN number is valid? false
Original PIN Number: 12345678
Is the said PIN number is valid? true
Original PIN Number: 123456789
Is the said PIN number is valid? false

Flowchart :

For more Practice: Solve these Related Problems:

• Write a Java program to validate that a PIN is exactly 4, 6, or 8 digits long using a regex pattern.
• Write a Java program to check if a given PIN contains only numeric characters and matches one of the allowed lengths.
• Write a Java program to implement a method that returns true if the PIN meets the specified length criteria, false otherwise.
• Write a Java program to design a PIN validation function that simultaneously checks for digit-only content and valid length.

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