Convert Binary to Decimal in Java

In the previous lesson, we covered the conversion of a Decimal to Binary. Here, you will learn how to convert Binary to Decimal in Java. There are a couple of ways:

• Using the parseInt() method
• With custom logic

Convert Binary to Decimal in Java using the parseInt() method

We can use the parseInt(String s, int radix) method of Integer class that parses the String argument as a signed integer in the radix specified by the second argument.

Example

class Test {

  public static void main(String[] args) {

    System.out.println(Integer.parseInt("1010", 2));
    System.out.println(Integer.parseInt("1001001", 2));
    System.out.println(Integer.parseInt("1100010", 2));
  }
}

Parse Binary to Decimal with custom logic

We can also write the program without using the pre-defined methods, like in the following example:

public class Test {

  public static void main(String[] args) {

    System.out.println(getDecimal(1010));
    System.out.println(getDecimal(1001001));
    System.out.println(getDecimal(1100010));
  }

  public static int getDecimal(int binary) {
    int decimal = 0;
    int n = 0;
    while (true) {
      if (binary == 0) {
        break;
      } else {
        int temp = binary % 10;
        decimal += temp * Math.pow(2, n);
        binary = binary / 10;
        n++;
      }
    }

    return decimal;
  }
}