Convert decimal to hexadecimal – java api, iterative & recursive

Leave a Comment / By Yogesh / September 12, 2016

Given a decimal number (base 10), convert decimal to hexadecimal number (base 16) using java.
We will discuss various methods to convert decimal number to hexadecimal number.
- Convert decimal to hexadecimal using Integer class
  - Integer.toHexString
  - Integer.toString
- Iterative program to convert decimal number to hexadecimal number.
- Recursive method to convert decimal number to hexadecimal number.

Methods – convert decimal to hexadecimal in java

1.) Convert decimal to hexadecimal using Integer.toHexString

private static String toHexString(int number) {
    return Integer.toHexString(number);
}

2.) Convert decimal to hexadecimal using Integer.toString

private static String toString(int number) {
    return Integer.toString(number, 16);
}

3.) Convert decimal to hexadecimal using iterative method

private static String iterative(int number) {
    StringBuilder builder = new StringBuilder();
    String hexCode = "0123456789ABCDEF";
     
    while (number > 0) {
        int hexDigit = number % 16;         
        builder.append(hexCode.charAt(hexDigit));
        number /= 16;
    }
    return builder.reverse().toString();
}

4.) Convert decimal to hexadecimal using recursive method

private static String recursive(int number) {
     StringBuilder builder = new StringBuilder();
    if (number>0) {
        String hexNumber = recursive(number/16);
        String hexCode = "0123456789ABCDEF";
        int hexDigit = number % 16;     
        builder.append(hexNumber + hexCode.charAt(hexDigit));
    }
    return builder.toString();
}

Complete program to convert decimal to hexadecimal

package org.learn;
 
import java.util.Scanner;
 
public class DecimalToHexDecimal {
 
    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            System.out.printf("1. Enter decimal number : ");
            int number = scanner.nextInt();
            String hexadecimal = toHexString(number);
 
            System.out.printf("2. Decimal to hexadecimal - toBinaryString(%d) = %s ", number, hexadecimal);
 
            hexadecimal = toString(number);
            System.out.printf("\n3. Decimal to hexadecimal - toString(%d) = %s ", number, hexadecimal);
 
            hexadecimal = iterative(number);
            System.out.printf("\n4. Decimal to hexadecimal - iterative(%d) = %s ", number, hexadecimal);
 
            hexadecimal = recursive(number);
            System.out.printf("\n5. Decimal to hexadecimal - recursive(%d) = %s ", number, hexadecimal);
        }
    }
 
    private static String toHexString(int number) {
        return Integer.toHexString(number);
    }
 
    private static String toString(int number) {
        return Integer.toString(number, 16);
    }
 
    private static String iterative(int number) {
        StringBuilder builder = new StringBuilder();
        String hexCode = "0123456789ABCDEF";
 
        while (number > 0) {
            int hexDigit = number % 16;
            builder.append(hexCode.charAt(hexDigit));
            number /= 16;
        }
        return builder.reverse().toString();
    }
 
    private static String recursive(int number) {
        StringBuilder builder = new StringBuilder();
        if (number > 0) {
            String hexNumber = recursive(number / 16);
            String hexCode = "0123456789ABCDEF";
            int hexDigit = number % 16;
            builder.append(hexNumber + hexCode.charAt(hexDigit));
        }
        return builder.toString();
    }
}

Program output – convert decimal to hexadecimal

Enter decimal number : 25
Decimal to hexadecimal - toBinaryString(25) = 19
Decimal to hexadecimal - toString(25) = 19
Decimal to hexadecimal - iterative(25) = 19
Decimal to hexadecimal - recursive(25) = 19
 
Enter decimal number : 31
Decimal to hexadecimal - toBinaryString(31) = 1f 
Decimal to hexadecimal - toString(31) = 1f 
Decimal to hexadecimal - iterative(31) = 1F 
Decimal to hexadecimal - recursive(31) = 1F 
 
Enter decimal number : 255
Decimal to hexadecimal - toBinaryString(255) = ff 
Decimal to hexadecimal - toString(255) = ff 
Decimal to hexadecimal - iterative(255) = FF 
Decimal to hexadecimal - recursive(255) = FF 