Discussion of Activity 10.5 - Using high level interfaces

The solution for part 3 of this activity is shown below.

package textboxexample;

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

public class TextBoxExample extends MIDlet implements CommandListener
{
   private TextBox textbox;
   private Display display;
   private static final int screenLength = 100;

   //commands
   private static final Command STOP = new Command("Stop", Command.EXIT,0);
   private static final Command CLEAR = new Command("Clear Screen", Command.SCREEN,1);
   private static final Command GO = new Command("GO",Command.SCREEN,1);

   private static final Command LOGO = new Command("LOGO",Command.SCREEN,1);
 
   public TextBoxExample()
   {
   }
 
   public void startApp()
   {
      textbox = new TextBox("TextBoxExample",
         "Delete this text and enter your own, then select option GO from the menu",
          screenLength,TextField.ANY);

      //add commands
      textbox.addCommand(STOP);
      textbox.addCommand(CLEAR);
      textbox.addCommand(GO);

      textbox.addCommand(LOGO);

      textbox.setCommandListener(this);
 
      //display the screen
      display = Display.getDisplay(this);
      display.setCurrent(textbox);
   }

   public void pauseApp()
   {
   }

   public void destroyApp(boolean b)
   {
   }

   //command Actions
   public void commandAction(Command c, Displayable d)
   {
      if (c == GO)
      {
         String text = textbox.getString();
         //create the Ticker
         Ticker ticker = new Ticker(text);
         textbox.setTicker(ticker);
      }
      if (c == STOP)
      {
         destroyApp(true);
         notifyDestroyed();
      }
      if (c == CLEAR)
      {
         textbox.setString(null);
      }

      if (c == LOGO)
      {
         String logo = "The Open University";
         Ticker ticker = new Ticker(logo);
         textbox.setTicker(ticker);
      }
   }
}

The solution for part 4 is to

1. add an import statement for the java.io library to the class in order to be able to handle the IOException that can now be thrown.

2. replace the last if clause in the commandAction method by code similar to the following:

   if (c == LOGO)
   {
      String logo = null;
      try
      {
         //access the resources folder
         InputStream is = getClass().getResourceAsStream("/res/logoFile.txt");
         InputStreamReader ir = new InputStreamReader(is);
         //create buffer
         char[] buffer = new char[100];
         StringBuffer sb = new StringBuffer();
         int count=0;
         //read in characters one by one
         while ((count = ir.read(buffer,0,buffer.length)) > -1)
         {
            sb.append(buffer,0,count);
         }
         logo = sb.toString();
      }
      catch (IOException ex)
      {
         logo = null;
      }
      //create the Ticker
      Ticker ticker = new Ticker(logo);
      textbox.setTicker(ticker);
   }
   
   

It is also important to remember to actually put the text file in the res folder!