Java convert binary to decimal

Let’s learn java convert binary to decimal.

Java convert binary to decimal

To convert from binary to decimal first user enters binary number using nextLine() method of Scanner class.

This binary number is stored in String variable ‘strBinary’. Now this string variable is converted using Integer.parseInt() method (inbuilt function).

In the next step each binary digit is multiplied with power of 2^a and added. Where ‘a’ is position of binary number from right side. Now let’s see program to convert binary to decimal using while loop.

import java.util.Scanner;
public class BinaryToDecimalDemo 
{
   public static void main(String[] args) 
   {
      int number, decimal = 0, a = 0;
      Scanner sc = new Scanner(System.in);
      System.out.println("Please enter binary number: ");
      String strBinary = sc.nextLine();
      number = Integer.parseInt(strBinary);
      while(number != 0){
         decimal += (number % 10) * Math.pow(2, a);
         number = number / 10;
         a++;
      }
      System.out.println("Decimal number: " + decimal);
      sc.close();
   }
}

Output:

Please enter binary number : 1111
Decimal number : 15

Let’s learn to convert binary to decimal conversion using custom logic.

public class BinaryToDecimalExample
{
   public int convertToBinary(int binary)
   {
      int decimal = 0;
      int b = 0;
      while(true)
      {
         if(binary == 0)
         {
            break;
         }
         else
         {
            int temp = binary % 10;
            decimal += temp * Math.pow(2, b);
            binary = binary / 10;
            b++;
         }
      }
      return decimal;
   }
   public static void main(String[] args)
   {
      BinaryToDecimalExample obj = new BinaryToDecimalExample();
      System.out.println("To decimal : " + obj.convertToBinary(110111));
   }
}

Output:

To decimal : 55

Binary to decimal using inbuilt function

Here let’s see to convert binary to decimal using Integer.parseInt() method. Here’s the syntax,

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

Integer.parseInt() method takes two arguments string and radix to which we have to convert the number.

Integer.parseInt() method returns the integer represented by the string argument in the specified radix.

This method parses the string argument as a signed integer in the radix specified by the second argument.

import java.util.*;
public class BinaryToDecimalDemo
{
   public static void main(String[] args)
   {
      String strBinary = "110111";
      int decimal = Integer.parseInt(strBinary, 2); 
      System.out.println(decimal);
   }
}

Output: