source code Konversi Biner ke Desimal dengan Bahasa Java

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package binergajilgenap;

import java.lang.*;
import java.io.*;
import java.util.Scanner;

/**
 *
 * @author andi m
 */
public class BinerGajilGenap {

    /**
     * @param args the command line arguments
     */
   public static void main ( String [] args ) throws IOException{
     Scanner input=new Scanner(System.in);
     System.out.print ( "Masukan Bilangan Binernya = " ) ;
     String str = input.nextLine();
     long num = Long.parseLong(str) ;
     long rem;
     while ( num > 0 ){
       rem = num % 10 ;
       num = num / 10 ;
       if ( rem != 0 && rem != 1 ){
         System.out.println ( "Ini bukan bilangan biner." ) ;
         System.out.println ( "Silahkan Coba lagi" ) ;
         System.exit ( 0 ) ;
       }
     }
     int i= Integer.parseInt ( str,2) ;
     System.out.println ( "Desimalnya : " + i ) ;
   }
}