E5.java

import java.util.Scanner; 
public class E5 { 
	public static void main(String[] args) 
	{ 
		Scanner input = new Scanner(System.in); 
		System.out.print("Enter a binary string: "); 
		String binaryString = input.next(); 
		System.out.println("The decimal equivalent of " + binaryString + " is " + bin2Dec(binaryString)); 
		} 
	public static int bin2Dec(String binaryString) { 
		int index = 0; 
		int n = binaryString.length() - 1; 
		int result = 0; 
		return bin2Dec( binaryString,index,n,result);	
	}
		public static int bin2Dec(String binaryString, int index, int n, int result) { 
			result += (Integer.parseInt(binaryString.charAt(index) + "") * (int)Math.pow(2, n));
		
		if (n == 0) { 
			return result; 
			}
		else 
			return bin2Dec(binaryString, index + 1, n - 1, result);
}
}