Convert binary to decimal in Java

In this post, you will learn how to convert a binary into an equivalent decimal number using Java programming language. Here, we have mentioned two ways to convert a binary to a decimal value.

A binary number consists of two numbers 0s and 1s. It is expressed in the base-2 numeral system or binary numeral system. As the computer only understands binary language that is 0 or 1, all inputs given to a computer are decoded by it into series of 0's or 1's to process it further. Any combination of 0 and 1 is a binary number such as 1011, 100, 101011, 111011 etc.

A decimal number is a base-10 number system. It ranges from 0 to 9 i.e., 0,1,2,3,4,5,6,7,8,9. Any combination of digits is a decimal number such as 61, 22, 912, 0, 5 etc. The main advantages of the decimal number system are easy-to-read, used by humans and easy to manipulate.

Java convert decimal to binary using Integer.parseInt() function

Java provides a built-in Integer.parseInt() function to convert various values to int with a given redix. This function returns a decimal value. Here is a simple example of converting binary to decimal in java.

// Java program to convert binary to decimal
public class ConvertBinaryToDecimal{  
    
    public static void main(String args[]){  
        System.out.println("Binary value of 1010 : "+Integer.parseInt("1010", 2));  
        System.out.println("Binary value of 1101 : "+Integer.parseInt("1101", 2));  
        System.out.println("Binary value of 1111 : "+Integer.parseInt("1111", 2));  
        System.out.println("Binary value of 1001 : "+Integer.parseInt("1001", 2));  
        System.out.println("Binary value of 1100 : "+Integer.parseInt("1100", 2));  
    }
}  

Binary value of 1010 : 10
Binary value of 1101 : 13
Binary value of 1111 : 15
Binary value of 1001 : 9
Binary value of 1100 : 12

Java convert binary to decimal using loop

Here, we have applied the custom logic using a loop to convert binary to decimal in Java.

public class ConvertBinaryToDecimal {
    
    // defining function to convert binary to decimal
    static int binaryToDecimal(int n)
    {
        int num = n;
        int decimal = 0;
 
        // Initializing base value to 1
        int base = 1;
 
        int temp = num;
        while (temp > 0) {
            int last_digit = temp % 10;
            temp = temp / 10;
 
            decimal += last_digit * base;
 
            base = base * 2;
        }
 
        return decimal;
    }
 
    // Driver Code
    public static void main(String[] args)
    {
        System.out.println("Decimal representation of 11001: "+binaryToDecimal(11001));
        System.out.println("\nDecimal representation of 10011: "+binaryToDecimal(10011));
        System.out.println("\nDecimal representation of 1001: "+binaryToDecimal(1001));
        System.out.println("\nDecimal representation of 1101: "+binaryToDecimal(1101));
    }
}

Decimal representation of 11001: 25

Decimal representation of 10011: 19

Decimal representation of 1001: 9

Decimal representation of 1101: 13

Java convert decimal to binary using custom method

In the given Java program, we have used the custom method to convert decimal to binary.

public class Main {
    
  public static void main(String[] args) {

    // binary number
    long num = 10011;

    // calling method 
    int decimal = convertBinaryToDecimal(num);

    System.out.println("Binary to Decimal");
    System.out.println(num + " = " + decimal);
  }

  public static int convertBinaryToDecimal(long num) {
    int decimalNum = 0, x = 0;
    long remainder;
    
    while (num != 0) {
      remainder = num % 10;
      num /= 10;
      decimalNum += remainder * Math.pow(2, x);
      ++x;
    }
    
    return decimalNum;
  }
}

Binary to Decimal
10011 = 19

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