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Creating CustomItem in Java ME

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(New page: __NOTOC__ __NOEDITSECTION__ {{CodeSnippet |id=  |platform=S60 3rd Edition, FP2 |devices=Nokia E70, Nokia N78 |category=Java ME |subcategory=UI |creationdate=November 5, 2008 |keywords...)
 
vltsoy (Talk | contribs)
Line 55: Line 55:
 
         form.addCommand(exitCommand);
 
         form.addCommand(exitCommand);
 
         form.setCommandListener(this);
 
         form.setCommandListener(this);
       
 
        myItem = new MyItem("Custom control");
 
        form.append(myItem);
 
 
          
 
          
 
         display = Display.getDisplay(this);
 
         display = Display.getDisplay(this);
 
         display.setCurrent(form);
 
         display.setCurrent(form);
 +
       
 +
        myItem = new MyItem("Custom control");
 +
        form.append(myItem);
 
     }
 
     }
  

Revision as of 17:22, 5 December 2008


Article Metadata
Tested with
Devices(s): Nokia E70, Nokia N78
CompatibilityArticle
Keywords: javax.microedition.lcdui.CustomItem
Created: (05 Nov 2008)
Last edited: vltsoy (05 Dec 2008)


Overview

This code snippet demonstrates how to create and display custom control. It consist of 2 files:

1. CustomControl.java - inherited from MIDlet, displays MyItem control.

2. MyItem.java - inherited from CustomItem.

Custom contol class MyItem implements method keyPressed(),which is responsible for storing last key pressed code. Also it implements method paint(), which displays 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 MIDlet, user will see custom control with last key pressed code.

Supplementary material

You can see source file and executable application in attached zip archive. Archive is available for download at Media:Creating_custom_control_in_J2ME.zip

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