In the previous article, we have discussed Java Program for Decimal to Hexadecimal

In this article we will see how to convert Binary to Decimal.

## Program for Binary to Decimal

So, before going into the program directly, let’s know about binary and decimal.

**Binary:**

Binary number mainly consists of only two numbers i.e. 0 and 1. The base address of the binary number is 2. For low voltage signal the value will 0 and for the high voltage signal the value will 1.

Example: (1001)2, (111000)2

Where 2 is the base. i.e `( )2`

**Decimal:**

Decimal number mainly defines the base of 10 in the number system. This number is basically consists of 10(ten) single digits like 0,1,2,3,4,5,6,7,8 and 9 with base 10. It is also known as a position value system.

Example: (183)10, (321)10

Where, 10 is the base. i.e `( )10`

Now, let’s see different ways to do it.

### Method-1: Java Program for Binary to Decimal By using Integer.ParseInt()

In this method we will use the inbuilt method `Integer.ParseInt()`

of Integer class.

**Approach:**

- Take a binary value and store it in an integer variable say
`binaryString`

. - Pass this binary value to
`Integer.ParseInt()`

method. - Then store the converted decimal value in an integer output variable say
.`decimal`

**Program:**

import java.util.*; public class BinaryToDecimal { public static void main(String args[]){ Scanner sc = new Scanner(System.in); System.out.println("Enter the binary string : "); String binaryString=sc.nextLine(); int decimal=Integer.parseInt(binaryString,2); System.out.println("The conversion of number " +binaryString+ " is : "+decimal); } }

Output: Enter the binary string : 10111 The conversion of number 1011 is : 23

### Method-2: Java Program for Binary to Decimal By using custom logic method

In this method we will convert the binary to decimal value by using custom method.

**Approach:**

- Take binary value as input from user.
- Pass this binary value to user defined method
`getDecimal()`

method where our binary to decimal conversion logic is present. - Then return the converted decimal value in long variable say
`decimal`

as output.

**Program:**

import java.util.*; public class Main { public static long getDecimal(long binary) { long decimal = 0; long n = 0; while(true){ if(binary == 0) { break; } else { long temp = binary%10; decimal += temp*Math.pow(2, n); binary = binary/10; n++; } } return decimal; } public static void main(String args[]) { Scanner sc=new Scanner(System.in); System.out.println("Enter two binary value : "); long n1=sc.nextLong(); long n2=sc.nextLong(); System.out.println("Decimal of "+n1+" is: "+getDecimal(n1)); System.out.println("Decimal of "+n2+" is: "+getDecimal(n2)); } }

Output: Enter two binary value : 10111 11 Decimal of 10111 is: 23 Decimal of 11 is: 3

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