Java Program for Decimal to Hexadecimal Conversion

There are two following ways to convert a decimal number to hexadecimal number:

1) Using toHexString() method of Integer class.
2) Do conversion by writing your own logic without using any predefined methods.

Program 1: Decimal to hexadecimal Using toHexString() method

The toHexString() method accepts integer number as argument and returns equivalent hexadecimal number as a String. The syntax of this method is:

public static String toHexString(int i)

Let’s write a program to convert a given int number to hex number.

class JavaExample
{
  public static void main(String args[])
  {
    //give int value
    int num = 10335;

    // toHexString() converts int to hex
    String str = Integer.toHexString(num);
    System.out.println("Decimal to Hexadecimal: "+str);
  }
}

Output:

Decimal to Hexadecimal: 285f

Get the input number from user: Same program as above, just used Scanner class to get the decimal number input from user.

import java.util.Scanner;
class DecimalToHexExample
{
    public static void main(String args[])
    {
      Scanner input = new Scanner( System.in );
      System.out.print("Enter a decimal number : ");
      int num =input.nextInt();
        
      // calling method toHexString()
      String str = Integer.toHexString(num);
      System.out.println("Method 1: Decimal to hexadecimal: "+str);
    }
}

Output:

Enter a decimal number : 123
Method 1: Decimal to hexadecimal: 7b

Program 2: Decimal to hexadecimal without using predefined method

In this method, we are not using the predefined method for conversion. We have written a logic to convert the given decimal number to hex.

import java.util.Scanner;
class DecimalToHexExample
{
   public static void main(String args[])
   {
     Scanner input = new Scanner( System.in );
     System.out.print("Enter a decimal number : ");
     int num =input.nextInt();
        
     // For storing remainder
     int rem;
        
     // For storing result
     String str2=""; 
 
     // Digits in hexadecimal number system
     char hex[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
 
     while(num>0)
     {
       rem=num%16; 
       str2=hex[rem]+str2; 
       num=num/16;
     }
     System.out.println("Method 2: Decimal to hexadecimal: "+str2);
  }
}

Output:

Enter a decimal number : 123
Method 2: Decimal to hexadecimal: 7B

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