BinaryToDecimal.java

import java.io.*;

public class BinaryToDecimal {
	public static void main(String[] args) {
    		//get the input data from user
		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
		System.out.print("Masukan Bilangan Binernya: ");
		String str = null;
		try {
			str = bf.readLine();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
    		//parse input data into Long
		long num = Long.parseLong(str);
		long rem;
		while (num > 0) {
			rem = num % 10;
			num = num / 10;
      			//check if the input data is binary or not
			if (rem != 0 && rem != 1) {
				System.out.println("Ini bukan bilangan biner.");
				System.out.println("Silahkan Coba lagi");
				System.exit(0);
			}
		}
    		//parse into integer
		int i = Integer.parseInt(str, 2);
    		//print out the result
		System.out.println("Desimalnya: " + i);
	}

}