Dear community,

I just started learning java a few weeks ago and needing a hand.

  • Need some help adding an error message when a user types in values out of range, in regard to the Hex user input where values have to be 0-9 and A to F.
  • I would also like to limit the user's input to just 2 digits/letters.

The program I am constructing is one which converts a Hexadecimal value to its Binary and Decimal equivalents.

Below is the code.

import java.util.Scanner;

public class Converter_6_ColinKagame {

public static void main(String args[]) {

// User is requested to type a Hex value

System.out.println("Please enter a Hexadecimal number : ");
Scanner scanner = new Scanner(;

//Two characters max can be input

//Is the value within valid range,
String hexadecimal =;

//Conversion: Hex to decimal

int decimal = Integer.parseInt(hexadecimal, 16);
System.out.println("Decimal equivalent is: " + decimal);

//Conversion: Hex to binary

String binary = Integer.toBinaryString(decimal);
System.out.printf("Binary equivalent for %s is: %s %n", hexadecimal, binary );