Java program to convert Decimal into Hexadecimal

By Vedant Nandkumar

This program is used to convert a decimal number into a hexadecimal number in Java.
A Decimal number employs 10 as a base and represents any number using 10 digits [0-9].
While
A Hexadecimal number employs 16 as a base and represent any number using 10 digits and 6 characters [0-9,A,B,C,D,E,F].

Hence, we can say we need to convert a number with base value 10 to base value 16.

There are 2 ways to convert a Decimal number to Hexadecimal number:

  1. Using the Integer.toHexString() method.
  2. Using our own logic to implement it unlike the predefined method in the above step.

Integer.toHexString() method to get Hexadecimal from Decimal

import java.io.*;
class DecimalToHex
{
    public static void main(String args[])throws IOException
    {  
       int n; //Defining decimal number
       BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
       System.out.println("Enter a decimal number: "); 
       n = Integer.parseInt(br.readLine()); //Entering the decimal number
       String hex= Integer.toHexString(n); //Using the predefined function
       System.out.println("The corresponding hexadecimal number is: "+hex); //Getting the required output
    } 
}

As shown above, the code is easily explained and easy to understand and implement.
It gives the following outputs for different inputs:

1)
Enter a decimal number: 
14
The corresponding hexadecimal number is: e
2)
Enter a decimal number: 
26
The corresponding hexadecimal number is: 1a
3)
Enter a decimal number: 
289
The corresponding hexadecimal number is: 121

Another way to convert Decimal into Hexadecimal in Java

import java.io.*;
class DecimalToHex
{
  public static void main(String args[])throws IOException
    {  
       int n,rem;
       String hexa=""; //rem is to store the remainder and hexa is to store the hexadecimal
       BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
       System.out.println("Enter a decimal number: ");
       n = Integer.parseInt(br.readLine());
       char hex[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};  //digits in hexadecimal system
       while(n>0)
       {
         rem=n%16; 
         hexa=hex[rem]+hexa; 
         n=n/16;
       }
       System.out.println("The corresponding hexadecimal number is: "+hexa);
    } 
}

As shown above, we have not used any predefined functions and solved it using our own logic simply by using arrays and while loop.
It gives the following output: (similar to the first way)

1)
Enter a decimal number: 
14
The corresponding hexadecimal number is: e
2)
Enter a decimal number: 
26
The corresponding hexadecimal number is: 1a

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