Complete Program

The program has become fairly long (60 lines!) But if you have gone through these notes step by step you will understand its structure, so the length is not a problem. Long programs are understood by understanding their pieces and how they fit together.

import java.io.*;

class LoopingLock
{
  public static void main( String[] args ) throws IOException
  {
    int lockFirst = 6, 
        lockSecond = 12, 
        lockThird = 30;
    int numb;

    BufferedReader stdin = new BufferedReader( 
        new InputStreamReader( System.in ) );
    String input;

    int     attempt     = 0;
    boolean open    = false;

    while ( attempt < 3 && !open )
    {
      // try a combination, setting open to "true" if correct

      boolean correct =  true;

      //First Number
      System.out.println("\nEnter first number: ");
      input = stdin.readLine();
      numb  = Integer.parseInt( input );

      if ( numb != lockFirst )    
        correct = false ;

      //Second Number
      System.out.println("Enter second number: ");
      input = stdin.readLine();
      numb  = Integer.parseInt( input );

      if ( numb != lockSecond )    
        correct = false  ;

      //Third Number
      System.out.println("Enter third number: ");
      input = stdin.readLine();
      numb  = Integer.parseInt( input );

      if ( numb != lockThird )    
        correct = false  ;

      //Result
      if ( correct )
      {
        System.out.println("Lock opens");
        open = true;
      }
      else
        System.out.println("Lock does not open");

      attempt = attempt + 1;
    }

  }
}