Re: I need a different approach - suggestions please

On 6/26/2012 1:04 PM, bilsch wrote:


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...
   }