//  SumMIDlet.java (c) Kari Laitinen

//  http://www.naturalprogramming.com

//  2003-11-??  File created.
//  2007-09-02  Last modification.

//  This program can calculate the sum of two integers which the user
//  inputs. TextField objects are used to receive data from the user.

//  The result of the calculation, i.e., the sum of the two integers,
//  is shown in an uneditable TextField. Another possibility to show the
//  result would be to use a StringItem object. However, it seems that
//  with an uneditable TextField it is easier to create a "nice" user
//  interface.

//  An old, equivalent version of this program is at the end of this file.

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;

public class SumMIDlet extends  MIDlet
                       implements CommandListener, ItemStateListener
{
   Display  display_of_this_midlet = Display.getDisplay( this ) ;

   TextField first_integer_text_field   = new TextField( "First integer: ",
                                                  "", 8, TextField.NUMERIC ) ;
   TextField second_integer_text_field  = new TextField( "Second integer:",
                                                  "", 8, TextField.NUMERIC )  ;
   TextField result_text_field     = new TextField( "Calculated sum:",
                                             "0", 8, TextField.NUMERIC |
                                                     TextField.UNEDITABLE ) ;

   Form  form_of_this_midlet  =  new  Form( "SumMIDlet" ) ;

   Command exit_command  =  new  Command( "EXIT", Command.EXIT, 1 ) ;

   public SumMIDlet()
   {
      first_integer_text_field.setLayout( Item.LAYOUT_CENTER ) ;

      form_of_this_midlet.append( first_integer_text_field ) ;
      form_of_this_midlet.append( second_integer_text_field ) ;
      form_of_this_midlet.append( result_text_field ) ;

      form_of_this_midlet.setItemStateListener( this ) ;

      form_of_this_midlet.addCommand( exit_command ) ;
      form_of_this_midlet.setCommandListener( this ) ;
   }

   protected void startApp() throws MIDletStateChangeException
   {
      display_of_this_midlet.setCurrent( form_of_this_midlet ) ;
   }

   protected void pauseApp()
   {
   }

   protected void destroyApp( boolean unconditional_destruction_required )
   {
   }

   public void commandAction( Command     given_command,
                              Displayable display_content )
   {
      if ( given_command  ==  exit_command )
      {
         destroyApp( false ) ;
         notifyDestroyed() ;
      }
   }

   public void itemStateChanged( Item item_which_changed_state )
   {
      String first_integer_text   =  first_integer_text_field.getString() ;
      String second_integer_text  =  second_integer_text_field.getString() ;

      if ( first_integer_text.length() ==  0 )
      {
         first_integer_text  =  "0" ;
      }

      if ( second_integer_text.length()  ==  0 )
      {
         second_integer_text  =  "0" ;
      }

      int first_integer   =  Integer.parseInt( first_integer_text ) ;
      int second_integer  =  Integer.parseInt( second_integer_text ) ;

      int sum_of_two_integers  =  first_integer  +  second_integer ;

      String  sum_text  =  "" + sum_of_two_integers ;

      result_text_field.setString( sum_text ) ;
   }
}


/*   The following is the old version of this program.
     The old version used an immutable TextField to show the calculation
     result.

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;

public class SumMIDlet extends  MIDlet
                       implements CommandListener, ItemStateListener
{
   private Display display_of_this_midlet ;

   private TextField first_integer_text_field ;
   private TextField second_integer_text_field ;
   private TextField result_text_field ;

   private Form  form_of_this_midlet  =  new  Form( "SumMIDlet" ) ;

   private Command exit_command  =  new  Command( "EXIT", Command.EXIT, 1 ) ;

   public SumMIDlet()
   {
      display_of_this_midlet  =  Display.getDisplay( this ) ;

      first_integer_text_field   = new TextField( "First integer: ",
                                                  "", 8, TextField.NUMERIC ) ;

      first_integer_text_field.setLayout( Item.LAYOUT_CENTER ) ;

      second_integer_text_field  = new TextField( "Second integer:",
                                                  "", 8, TextField.NUMERIC ) ;
      result_text_field     = new TextField( "Calculated sum:",
                                             "0", 8, TextField.NUMERIC |
                                                     TextField.UNEDITABLE ) ;

      form_of_this_midlet.append( first_integer_text_field ) ;
      form_of_this_midlet.append( second_integer_text_field ) ;
      form_of_this_midlet.append( result_text_field ) ;

      form_of_this_midlet.setItemStateListener( this ) ;

      form_of_this_midlet.addCommand( exit_command ) ;
      form_of_this_midlet.setCommandListener( this ) ;
   }

   protected void destroyApp( boolean conditional_destruction_disabled )
   {
   }

   protected void pauseApp()
   {
   }

   protected void startApp() throws MIDletStateChangeException
   {
      display_of_this_midlet.setCurrent( form_of_this_midlet ) ;
   }

   public void commandAction( Command     given_command,
                              Displayable display_content )
   {
      if ( given_command  ==  exit_command )
      {
         destroyApp( false ) ;
         notifyDestroyed() ;
      }
   }

   public void itemStateChanged( Item item_which_changed_state )
   {
      String first_integer_text   =  first_integer_text_field.getString() ;
      String second_integer_text  =  second_integer_text_field.getString() ;

      if ( first_integer_text.length() ==  0 )
      {
         first_integer_text  =  "0" ;
      }

      if ( second_integer_text.length()  ==  0 )
      {
         second_integer_text  =  "0" ;
      }

      int first_integer   =  Integer.parseInt( first_integer_text ) ;
      int second_integer  =  Integer.parseInt( second_integer_text ) ;

      int sum_of_two_integers  =  first_integer  +  second_integer ;

      String  sum_text  =  "" + sum_of_two_integers ;

      result_text_field.setString( sum_text ) ;
   }
}









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