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

public class EventEx1 extends MIDlet implements CommandListener {
   // display manager
   Display display = null;
    
   // a menu with items
   List menu = null; // main menu

   // textbox
   TextBox input = null;

   // command
   static final Command backCommand = new Command("Back", Command.BACK, 0);
   static final Command mainMenuCommand = new Command("Main", Command.SCREEN, 1);
   static final Command exitCommand = new Command("Exit", Command.STOP, 2);
   String currentMenu = null;

   // constructor.
   public EventEx1() {
   }

   /**
    * Start the MIDlet by creating a list of items and associating the
    * exit command with it.
    */
   public void startApp() throws MIDletStateChangeException {
      display = Display.getDisplay(this);
      menu = new List("Menu Items", Choice.IMPLICIT);
      menu.append("Item1", null);
      menu.append("Item2", null);
      menu.append("Item3", null);
      menu.append("Item4", null);
      menu.addCommand(exitCommand);
      menu.setCommandListener(this);

      mainMenu();
   }

   public void pauseApp() {
      display = null;
      menu = null;
      input = null;
   }

   public void destroyApp(boolean unconditional) {
      notifyDestroyed();
   }

   // main menu
   void mainMenu() {
      display.setCurrent(menu);
      currentMenu = "Main"; 
   }

   /**
    * a generic method that will be called when selected any of
    * the items on the list.
    */
   public void prepare() {
      input = new TextBox("Enter some text: ", "", 5, TextField.ANY);
      input.addCommand(backCommand);
      input.setCommandListener(this);
      input.setString("");
      display.setCurrent(input);
   }

   /**
    * Test item1.
    */
   public void testItem1() {
      prepare();
      currentMenu = "item1";
   }
   
   /**
    * Test item2.
    */
   public void testItem2() {
      prepare();
      currentMenu = "item2"; 
   }

   /**
    * Test item3.
    */
   public void testItem3() {
      prepare();
      currentMenu = "item3"; 
   }

   /**
    * Test item4.
    */
   public void testItem4() {
      prepare();
      currentMenu = "item4"; 
   }

   /**
    * Handle events.
    */  
   public void commandAction(Command c, Displayable d) {
      String label = c.getLabel();
      if (label.equals("Exit")) {
         destroyApp(true);
      } else if (label.equals("Back")) {
         if(currentMenu.equals("item1") || currentMenu.equals("item2") ||
            currentMenu.equals("item3") || currentMenu.equals("item4"))  {
            // go back to menu
            mainMenu();
         } 

      } else {
         List down = (List)display.getCurrent();
         switch(down.getSelectedIndex()) {
            case 0: testItem1();break;
            case 1: testItem2();break;
            case 2: testItem3();break;
            case 3: testItem4();break;
         }
      }
   }
}