Java convert hex to decimal

by January 11, 2017 Java programs

Let’s learn java convert hex to decimal.

Java convert hex to decimal

Java program that converts a hexadecimal number to a decimal number is one of the frequently asked java program interview question.

In hexadecimal to decimal conversion we are using Integer.parseInt() method.

Integer.parseInt() method parses string argument as a signed integer in the radix specified by the second argument.

Here’s the syntax.

public static int parseInt(String s, int radix) throws NumberFormatException

Let’s see java program.

public class ConvertHexToDecimal
{
   public static void main(String[] args)
   {
      String strHex = "b";
      int decimal = Integer.parseInt(strHex, 16);
      System.out.println("Decimal number : " + decimal);
   }
}

Output:

Decimal number : 11

Hexadecimal to decimal java user input

Meanwhile to we can convert hexadecimal to decimal based on user input. For this we need Scanner class.

Logic to convert a hexadecimal to a decimal number is same as above java program.

Now let’s see hexadecimal to decimal java user input.

import java.util.Scanner;
public class HexToDecimalDemo 
{
   public static void main(String[] args) 
   {
      Scanner sc = new Scanner(System.in);
      System.out.println("Please enter hexadecimal number: ");
      String strHexNumber = sc.nextLine();    
      // converting hexadecimal to decimal by passing base 16 
      int decimalNumber = Integer.parseInt(strHexNumber, 16);
      System.out.println("Converting hexadecimal to decimal: " + decimalNumber);
      sc.close();
   }
}

Output:

Please enter hexadecimal number: 6A
Converting hexadecimal to decimal: 106

Similarly we can convert hexadecimal to decimal number using user defined method.

public class HexaToDecimal
{
   public static int convertHexadecimal(String strHex)
   {
      String Hexadecimal = "0123456789ABCDEF";
      strHex = strHex.toUpperCase();
      int value = 0;
      for(int a = 0; a < strHex.length(); a++)
      {
         char ch = strHex.charAt(a);
         int d = Hexadecimal.indexOf(ch);
         value = 16 * value + d;
      }
      return value;
   }
   public static void main(String[] args)
   {
      System.out.println("Decimal value of b is : " + convertHexadecimal("b"));
      System.out.println("Decimal value of d is : " + convertHexadecimal("d"));
      System.out.println("Decimal value of 151 is : " + convertHexadecimal("151"));
   }
}

Output:

java convert hex to decimal

Also read – garbage collection in java