Question

Covert a Hexadecimal to decimal (there is a video for you to watch too). Then write a program that can convert a binary to decimal (only for integer case).

There are two ways to do so.

Easy way: Directly use Java built-in method to do this. In this case, only couple lines of code. Hint: Study Integer class in Java.

Hard way: Write your own code to convert a binary to decimal from scratch. The input is a binary string. The program output is its corresponding decimal value. This way you need to design the algorithm.

Answer 1

//HexToDecimal.java

import java.lang.*;
import java.util.Scanner;
public class HexToDecimal
{
   public static void main(String[] args) {
       Scanner sc = new Scanner(System.in);
       System.out.print("Enter Hex number : ");
       String hex = sc.nextLine();//Take input from user
       hex = hex.toUpperCase();//To convert all characters to uppercase
       //Direct conversion using built-in function from Integer Class
       int decimal = Integer.parseInt(hex,16);
       System.out.println("conversion hex-decimal using Integer class : "+hex+" -> "+decimal);

       //Building our own method to convert hex to decimal

       String numbers = "0123456789ABCDEF";
       int value = 0;
       for(int index = 0; index < hex.length(); index++){
           char ch = hex.charAt(index);
           int digit = numbers.indexOf(ch);
           value = 16*value + digit;
       }
       System.out.println("conversion hex-decimal using our algorithm : "+hex+" -> "+value);
   }
}

//OUTPUT

//BINARYTODECIMAL.JAVA

import java.lang.*;
import java.util.Scanner;
public class BinaryToDecimal
{
   public static void main(String[] args) {
       Scanner sc = new Scanner(System.in);
       System.out.print("Enter Binary number : ");
       String binary = sc.nextLine();//Take input from user
       //Direct conversion using built-in function from Integer Class
       int decimal = Integer.parseInt(binary,2);
       System.out.println("conversion binary-decimal using Integer class : "+binary+" -> "+decimal);

       //Building our own method to convert binary to decimal

       int value = 0,power=0;
       for(int index = binary.length()-1; index >=0 ; index--){
           char ch = binary.charAt(index);
           int digit = ch - '0';//To get 0 or 1
           value += digit*Math.pow(2,power);
           power++;
       }
       System.out.println("conversion binary-decimal using our algorithm : "+binary+" -> "+value);
   }
}

//OUTPUT