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From: markspace <-@.>
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Subject: Re: I need a different approach - suggestions please
Date: Tue, 26 Jun 2012 14:25:27 -0700
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On 6/26/2012 1:04 PM, bilsch wrote:

> Now that you mention it I see how that would work.  However the actual
> program has many non-numeric buttons I don't want in the string - I
> better leave that alone for the present.


A couple of things.  First, even if true, it's better to do something 
like this:

   if( btn == "1" || btn == "2" || btn == "3" ... )
   {
       // one single case here...
   }

Than it is to use many different if-blocks.  Same action for different 
inputs, you want to use one code block to implement that action.

One other important point I'd like to make is that Java strings don't 
normally compare with ==.  You have to use .equals() instead.  Your code 
works now because all of the strings are in a single file, but as your 
program grows == will no longer work for you.

This is the normal, and more correct, way to do it:

   if( btn.equals( "1" ) || btn.equals( "2" ) || ... )
   {
      strng1 += btn;
   }

Lastly, given your specific use case, there's a cheap quick way to cut 
down on verbosity.  It involves knowing the API well, but String and 
Math (and a few others) are two APIs that you should memorize eventually 
to be a good Java programmer.  (Other APIs it's OK to have to consult 
the documentation periodically.)

   String digits = "0123456789.";
   String opers = "+-/*";
   String clear = "Clear";

   if( digits.contains( btn ) ) {
      strng1 += btn;
   } else if( opers.contains( btn ) ) {
      // go do some math
   } else if( clear.equals( btn ) ) {
      strng1 = "0";
   }

Note the above block is untested. Caveat emptor.

Later you'll be able to do the same thing with objects that aren't 
strings with the Set class.

   Set stuff1 = ...

   if( stuff1.contains( potentialMember ) ) {
      // take an action...
   }