How To Convert Binary To Decimal In Java?

If you want to mention multiple binary numbers in the code itself, you can mention in the following way:

package sampleprogram;
public class ConvertBinaryToDecimal {
public static void main(String args[]){
System.out.println(Integer.parseInt("1110",2));
System.out.println(Integer.parseInt("0010",2));
System.out.println(Integer.parseInt("1010",2));
System.out.println(Integer.parseInt("0110",2));
System.out.println(Integer.parseInt("1101",2));
}
}

Output:

Ask the user to enter the binary number

To make the user input the binary number, you have to import the Scanner class. The Scanner class is mainly used to get the user input, and it belongs to the java.util package.

package sampleprogram;
import java.util.Scanner;
public class ConvertBinaryToDecimal {
public static void main(String args[]){
Scanner BinaryInput = new Scanner( System.in );
System.out.print("Enter the Binary Number - ");
String BinaryNumber =BinaryInput.nextLine();
System.out.println("Decimal Number- "+Integer.parseInt(BinaryNumber,2));
}
}

Output:

Well, folks, that was about writing a java program using the Integer.parseInt() method. Now, next in this article on converting binary to decimal in java, let us see how to write a Java program for conversion of binary to decimal numbers without using the Integer.parseInt() method.

Java program using custom logic

To write a Java program on how to convert a binary number to decimal number without using the Integer.parseInt() method, you can either write code by mentioning the binary numbers in the code itself or by taking the user input.

Mention the binary number in the program itself

package sampleprogram;
public class ConvertBinaryToDecimal {
public static int retrieveDecimal(int binarynumber){
int decimalnumber = 0;
int power = 0;
while(true)
{
if (binarynumber == 0)
{
break;
}
else
{
int temp = binarynumber%10;
decimalnumber += temp*Math.pow(2, power);
binarynumber = binarynumber/10;
power++;
}
}
return decimalnumber;
}
public static void main(String args[]){
System.out.println("Decimal value is: "+retrieveDecimal(1110));
System.out.println("Decimal value is: "+retrieveDecimal(0010));
System.out.println("Decimal value is: "+retrieveDecimal(1010));
System.out.println("Decimal value is: "+retrieveDecimal(0110));
System.out.println("Decimal value is: "+retrieveDecimal(1101));
}
}

Output:

Ask the user to enter the binary number

package sampleprogram;
import java.util.Scanner;
class ConvertBinaryToDecimal
{
public static void main(String args[])
{
Scanner binaryinput=new Scanner(System.in);
System.out.println("Enter the binary number-");
int n=binaryinput.nextInt();
int decimalnumber=0,power=0;
while(n!=0)
{
decimalnumber+=((n%10)*Math.pow(2,power));
n=n/10;
power++;
}
System.out.println(decimalnumber);
}
}

Output: