Emerging Technology Fall Semester, 2004 MIDlet UI
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CS 683 Emerging Technologies Fall Semester, 2004 Doc 19 MIDlet UI

Contents

References

Input From Files in Jar

Hi-Level UI Components

TextBox

Basic TextBox

TextBox with Timer

TextBox with Command

Copyright ©, All rights reserved. 2004 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA. OpenContent ( http://www.opencontent.org/opl.shtml) license defines the copyright on this document.

References

J2ME in a Nutshell, Kim Topley, O’Reilly, 2002, Chapter 3 & 4

Examples in this lecture are based on examples in the above reference

Lecture Source Code

Input From Files in Jar

Embedding UI text strings in code is a poor idea

Put them in files

Add the files to the application jar file

Files

• src/HelloMIDlet.java
• res/Text.txt

res/Text.txt

Hello World from a file

src/HelloMIDlet.java

import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import javax.microedition.midlet.MIDlet;
import javax.microedition.lcdui.*;
   
public class HelloMIDlet extends MIDlet {   
   
   public HelloMIDlet() {
      Form form = new Form( "Hi Mom"  );
      form.append( readFile()  );
      Display.getDisplay(this).setCurrent( form );
   }
   
   private String readFile()  {
      try {
         InputStream byteInput = 
               getClass().getResourceAsStream("/Text.txt");
         InputStreamReader characterInput = 
               new InputStreamReader(byteInput);
         char[] buffer = new char[32];
         StringBuffer stringBuffer = new StringBuffer();
         int count;
         while ((count = characterInput.read(buffer, 0, buffer.length)) > -1) {
            stringBuffer.append(buffer, 0, count);
         }
         return stringBuffer.toString();
      }
      catch (Exception ioProblem)  {
         return "Could not read file";
      }
   }
   
CS 683 Fall 04
Doc 19, MIDlet UI Slide # 5

Source Continued

   public void startApp() {}
   public void pauseApp() { }
   
   public void destroyApp( boolean unconditional ) { }
}

Two Ways to reference the file

Absolute

getClass().getResourceAsStream("/foo/bar/Text.txt");

Path is from the top level of the jar file

Relative

getClass().getResourceAsStream("/foo/bar/Text.txt");

Path is from the location of the location of the class in the jar file

Hi-Level UI Components

TextBox

Textbox Documemtation

http://www.eli.sdsu.edu/courses/fall04/cs683/j2me/docs/api/midp/javax/microedition/lcdui/TextBox.html

Input Constraints

http://www.eli.sdsu.edu/courses/fall04/cs683/j2me/docs/api/midp/javax/microedition/lcdui/TextField.html

Basic TextBox

Based on example, pages 89-90, J2ME in a Nutshell, Kim Topley, O’Reilly

import java.io.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;
   
public class TextBoxMIDlet extends MIDlet  {
   private static final int MAX_TEXT_SIZE = 80;
   protected TextBox textBox;
   protected Display display;
    
   
   public TextBoxMIDlet() {
      textBox = new TextBox("TextBox Example", readFile("/Text.txt"), 
                     MAX_TEXT_SIZE, TextField.ANY);
      
      Ticker ticker = new Ticker("This is a ticker...");
      textBox.setTicker(ticker);
      
      display = Display.getDisplay(this);            
      display.setCurrent(textBox);
   }
   
   public void startApp() { }
   public void pauseApp() { }
   public void destroyApp( boolean unconditional ) { }

Basic TextBox Continued

   private String readFile(String filename)  {
      try {
         InputStream byteInput = getClass().getResourceAsStream(filename);
         InputStreamReader characterInput = new InputStreamReader(byteInput);
         char[] buffer = new char[32];
         StringBuffer stringBuffer = new StringBuffer();
         int count;
         while ((count = characterInput.read(buffer, 0, buffer.length)) > -1) {
            stringBuffer.append(buffer, 0, count);
         }
         return stringBuffer.toString();
      }
      catch (Exception ioProblem) {
         return "Could not read file";
      }
   }
}

TextBox with Timer

Based on examples, pages 73-74, 89-90, J2ME in a Nutshell

import java.io.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;
import java.util.*;
   
public class ThreadTextBoxMIDlet extends MIDlet  {    
   private static final int MAX_TEXT_SIZE = 80;
   protected TextBox textBox;
   private Timer timer;
   private int count = 0;
    
   public ThreadTextBoxMIDlet() {
      textBox = new TextBox("Timer Example", "Hello for now", 
                     MAX_TEXT_SIZE, TextField.ANY);      
      Display.getDisplay(this).setCurrent(textBox);
   }
   
   public void startApp()  { 
      if (timer == null)
         startTimer();
      else
         count = 0;
   }

TextBox with Timer Continued

   public void pauseApp()  {
      textBox.setString("Here we go again");
   }
   
   public void destroyApp( boolean unconditional )  { 
      stopTimer();
   }
      
   private void startTimer()  {
      TimerTask addCount = new TimerTask() {
        
         public void run() {
            textBox.setString( "" + count++);
            if (count == 10) 
               notifyPaused();
            else if (count > 15)
               resumeRequest();
         }
      };
        
      timer = new Timer();
      timer.schedule(addCount, 2000, 1000); 
   }
    
    private void stopTimer()  {
      if (timer != null) 
         timer.cancel();
   }
}
CS 683 Fall 04
Doc 19, MIDlet UI Slide # 13

TextBox with Command

Based on example, pages 99-100, J2ME in a Nutshell

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Displayable;
   
public class CommandTextBoxMIDlet extends TextBoxMIDlet 
      implements CommandListener {
   
   private static final Command EXIT_COMMAND = 
                  new Command("Exit", Command.EXIT, 0);
   
   private static final Command OK_COMMAND =
                  new Command("OK", Command.OK, 0);
   
   private static final Command CLEAR_COMMAND =
                  new Command("Clear", Command.SCREEN, 1);
   
   private static final Command REVERSE_COMMAND =
                  new Command("Reverse", Command.SCREEN, 1);
   
   public  CommandTextBoxMIDlet() {   
      super();      
      textBox.addCommand(OK_COMMAND);         
      textBox.addCommand(EXIT_COMMAND);
      textBox.addCommand(CLEAR_COMMAND);         
      textBox.addCommand(REVERSE_COMMAND);         
      textBox.setCommandListener(this);
   }

TextBox with Command Continued

   public void commandAction(Command c, Displayable d) {
      if (c == EXIT_COMMAND) {
         destroyApp(true);
         notifyDestroyed();
      } else if (c == OK_COMMAND) {
         textBox.setString("OK pressed");
      } else if (c == CLEAR_COMMAND) {
         textBox.setString(null);
      } else if (c == REVERSE_COMMAND) {
         String str = textBox.getString();
         if (str != null) {
            StringBuffer sb = new StringBuffer(str);
            textBox.setString(sb.reverse().toString());
         }         
      }
   }   
}

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