BlackBerry - KeyListener with global scope - blackberry

Question

I am new to BlackBerry App development. I want to be able to listen for keypress events whenever the BlackBerry (8900 in my case) is on and on all screens is this possible?
If so, it would be great for someone to direct me in the right direction. I am already having a look at Interface KeyListener.
import net.rim.device.api.system.*;
Thanks all

Answer 1

Implement a keylistenerClass like:
import model.Profile;
import net.rim.device.api.system.KeyListener;
import net.rim.device.api.ui.Keypad;
public final class ShortcutHandler implements KeyListener {
public boolean keyChar(char key, int status, int time) {
return false;
}
public boolean keyDown(int keycode, int time) {
if (Keypad.KEY_ESCAPE == Keypad.key(keycode)) {
// Consume the event.
// Here I'm consuming the event for the escape key
return true;
}
//let the system to pass the event to another listener.
return false;
}
public boolean keyRepeat(int keycode, int time) {
return false;
}
public boolean keyStatus(int keycode, int time) {
return false;
}
public boolean keyUp(int keycode, int time) {
return false;
}
}
Then in your application constructor
public Application() {
//Add the listener to the system for this application
addKeyListener(new ShortcutHandler());
}
I confirm that it's working when the application is in the background.

Answer 2

As I understood, you want to listen to all key events in all applications running on device, not only in your application.
I think it's not possible.
UPDATE
How does the volume up and down key work? – Abs 11 hours ago
If you want to say that all applications receive key events from volume keys, thats not true. RIM OS will receive those events and then update all audio components like alert, audio, player etc.
you can easely check it with this sample:
Do following:
run sample
enter some key events
look at events number
go background
enter some key events
go back to sample by menu->switch application
check events number, it still the same
Code:
import net.rim.device.api.system.KeyListener;
import net.rim.device.api.ui.MenuItem;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.component.Menu;
import net.rim.device.api.ui.container.MainScreen;
public class KeyListenerApp extends UiApplication implements KeyListener {
Scr mScreen;
public KeyListenerApp() {
mScreen = new Scr();
pushScreen(mScreen);
addKeyListener(this);
}
public static void main(String[] args) {
KeyListenerApp app = new KeyListenerApp();
app.enterEventDispatcher();
}
private void updateScreen(final String text) {
mScreen.addLine(text);
}
public boolean keyChar(char key, int status, int time) {
updateScreen("keyChar " + key);
return true;
}
public boolean keyDown(int keycode, int time) {
updateScreen("keyDown " + keycode);
return true;
}
public boolean keyRepeat(int keycode, int time) {
updateScreen("keyRepeat " + keycode);
return true;
}
public boolean keyStatus(int keycode, int time) {
updateScreen("keyStatus " + keycode);
return true;
}
public boolean keyUp(int keycode, int time) {
updateScreen("keyUp " + keycode);
return true;
}
}
class Scr extends MainScreen {
int mEventsCount = 0;
LabelField mEventsStatistic = new LabelField("events count: "
+ String.valueOf(mEventsCount));
public Scr() {
super(VERTICAL_SCROLL | VERTICAL_SCROLLBAR);
add(mEventsStatistic);
}
public void addLine(final String text) {
getApplication().invokeLater(new Runnable() {
public void run() {
mEventsStatistic.setText("events count: "
+ String.valueOf(++mEventsCount));
insert(new LabelField(text), 1);
}
});
}
protected void makeMenu(Menu menu, int instance) {
super.makeMenu(menu, instance);
menu.add(goBGMenuItem);
}
MenuItem goBGMenuItem = new MenuItem("go backgroun", 0, 0) {
public void run() {
getApplication().requestBackground();
}
};
}

Answer 3

This how I imagine it could work
create application which extends UiApplication or even Application
create an implementation of Keylistener (which could also extend Thread if you want)
add your KeyListener implementation to your application via addKeyListener()
Then do whatever you want.

Answer 4

The code given above certainly works, but there is a catch. You wont be able to trap the key presses on native apps like call handling sms incoming browsing and stuff. As system generates global event to these apps. Its like you are able to define a routine for clicks when your app is in background , but the functionality of that routine is localised to your application only. It wont effect other apps as such.