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Creating CustomItem in Java ME

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Article Metadata
Code ExampleTested with
Devices(s): Nokia 6131, Nokia E70, Nokia N78, Nokia C3-01
CompatibilityArticle
Created: vltsoy (27 Nov 2008)
Last edited: hamishwillee (13 Aug 2013)

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Contents

Overview

This code snippet demonstrates how to create and display custom control. It consist of two files:

  1. CustomControl.java - Inherited from MIDlet, displays the MyItem control.
  2. MyItem.java - Inherited from CustomItem.

Custom contol class MyItem implements the method keyPressed(), which is responsible for storing the last key-pressed code. It also implements the paint() method, which displays the last key-pressed code inside the control.


Source file: CustomControl.java

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.midlet.MIDlet;
 
 
public class CustomControl extends MIDlet implements CommandListener{
//Main form.
 
private Form form;
private Display display;
private Command exitCommand;
private MyItem myItem;
 
/**
* Constructor. Constructs the object and initializes displayables.
*/

public CustomControl() {
form = new Form("Custom Control MIDlet.");
 
// Add command buttons
exitCommand = new Command("Exit", Command.EXIT, 1);
form.addCommand(exitCommand);
form.setCommandListener(this);
 
display = Display.getDisplay(this);
display.setCurrent(form);
 
myItem = new MyItem("Custom control");
form.append(myItem);
}
 
/**
* From CommandListener.
* Called by the system to indicate that a command has been invoked on a
* particular displayable.
* @param cmd the command that was invoked
* @param displayable the displayable where the command was invoked
*/

public void commandAction(Command cmd, Displayable displayable) {
if (cmd == exitCommand) {
notifyDestroyed();
}
}
 
/**
* From MIDlet.
* Called when the MIDlet is started.
*/

public void startApp() {
// No implementation required.
}
 
/**
* From MIDlet.
* Called to signal the MIDlet to enter the Paused state.
*/

public void pauseApp() {
// No implementation required.
}
 
/**
* From MIDlet.
* Called to signal the MIDlet to terminate.
* @param unconditional whether the MIDlet has to be unconditionally
* terminated
*/

public void destroyApp(boolean unconditional) {
// No implementation required.
}
}

Source file: MyItem.java

import javax.microedition.lcdui.CustomItem;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
 
class MyItem extends CustomItem {
// Last key pressed code.
private int key;
 
/**
* Constructor.
*/

public MyItem( String label ){
super( "" );
}
 
/**
* From CustomItem.
* Called by the system to redraw canvas.
* @param graphics used for drawing operations.
*/

public void paint(Graphics g, int width, int height) {
//Display last key pressed.
String output = "Key code:"+String.valueOf(key);
 
g.drawString(output,(width-g.getFont().stringWidth(output))/2,
(height-g.getFont().getHeight())/2, 0);
 
g.setStrokeStyle(Graphics.DOTTED);
for (int i= 0;i<(height+width)/10;i++)
{
g.setColor(i*10000);
g.drawRect( 0+i, 0+i, (width-i*2), (height-i*2));
}
}
 
/**
* From CustomItem.
* Called by the system to retrieve minimum width required for this control.
*/

protected int getMinContentWidth() {
return 150;
}
 
/**
* From CustomItem.
* Called by the system to retrieve minimum height required for this control.
*/

protected int getMinContentHeight() {
return 100;
}
 
/**
* From CustomItem.
* Called by the system to retrieve preferred width for this control.
*/

protected int getPrefContentWidth(int arg0) {
return 200;
}
 
/**
* From CustomItem.
* Called by the system to retrieve preferred height for this control.
*/

protected int getPrefContentHeight(int arg0) {
return 100;
}
 
/**
* From CustomItem.
* Called by the system to redraw canvas.
* @param graphics used for drawing operations.
*/

protected void keyPressed(int keyCode) {
key = keyCode;
this.repaint();
}
}

Postconditions

After starting the MIDlet, the user will see custom control with the last key-pressed code.

Custom item.png

Supplementary material

You can view the source file and executable application in the attached zip archive. The archive is available for download at Media:Creating custom control in J2ME.zip

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This page was last modified on 13 August 2013, at 09:28.
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