Re: Help with Java program

On 11/11/2010 4:53 AM, DeAndrea Monroe wrote:


Here's some basic computer science info, if your instructor isn't
teaching. The classic computer program consists of three parts:

1. Input
2. Processing
3. Output

These steps run in that order. This worked for a long time, for punch
cards and green terminals, up until modern GUIs and MVC. However, many
small parts of a computer program, such as the controllers used in an
MVC design, can still be broken into those three parts, so the concept
is still useful.

Banking programs like yours can often be broken into these three parts.
  The customer provides some input (their account number and a dollar
amount), you process it (withdrawal/deposit), then give the user his
result ($$, account report, no funds, etc.).

I had a friend in college who was pretty dyslexic. He would write is
programs as a kind of outline, to make sure he had the structure
correct, then fill in the "blanks" to produce output.

For example, your banking program might start like this:

public class Banking2 {
   public static void main( String... arg ) {
     System.out.println( "Hello Banking World" );
   }
}

Once you get that working, add a bit of outline for the steps above.

public class Banking2 {
   public static void main( String... arg ) {
     System.out.println( "Hello Banking World" );
     input();
     processing();
     output();
   }
   private static void input() {
   }
   private static void processing() {
   }
   private static void output() {
   }
}

Now, get that running, just as it is. It won't do anything different,
but you won't waste time with braces missing or other basic errors,
because the braces are easy to see.

Continue adding small steps until you have something working.

To test, you may have to add extra debugging (println's work well) so
you can verify that you've the work correctly. These println's will
help you keep the program working as you modify it, so don't remove
them. If you make a new class, add a toString() method so it will print
easily and correctly.

For the final program, once you are sure it's all working, don't remove
the println's, just comment them out, so you can add them back if you
decide you need to make more changes.

public class Banking2 {

   static List<CustInput> queue = new List<CustInput>();

   class CustInput {
     int accountNum;
     char withdrawalDeposit;
     int amount; // in cents
     @Override
     public String toString() {
        return "(account num:"+accountNum+
        " with/dep:"+withdrawalDeposit+
        " ammount:"+ammount+")";
     }
   }

   public static void main( String... arg ) {
     System.out.println( "Hello Banking World" );
     input();
     processing();
     output();
   }

   private static void input() {
      for( int i = 0; i < 5; i++ ) {
        CustInput trans = new CustInput();
        trans.accountNum = i;
        trans.withdrawalDepsoit = 'D';
        trans.amount = i * 100;
        queue.add( trans );
     }
     // now print to make sure we did that right
     System.out.println( "Queue after first input step:" );
     System.out.println( queue );
   }

   private static void processing() {
   }
   private static void output() {
   }
}

Now I did all that with out checking it, so it'll probably have some
typos. I'll let you work out where they might be. I'm pretty sure I
got at least the first program correct.