Event handling betwwen two canvas classes

Question

Hi again!
I have two canvas classes: MainCanvas and SubCanvas.
SunCanvas has keyPressed() method implemented and it's working perfectlly. The only problem is when a certain key is pressed, say Select, I want MainCanvas to be notified.
anybody have an idea?
I tried with CommandListener but I can't work it out. Can i 'active' an event through Cammandlistener maybe?
cheers
Indy

Answer 1

You have two choices here.
The first is like you said using CommandListener. If you add a Command to your SubCanvas, and then set the MainCanvas as the CommandListener, then the MainCanvas gets notified if the command is selected through the commandAction() method:
class SubCanvas extends Canvas {
  Command something = new Command("Hi",Command.OK,1);
  public SubCanvas(MainCanvas mc) {
    addCommand(something);
    setCommandListener(mc);
class MainCanvas extends Canvas implements CommandListener {
  public void commandAction(Command c, Displayable d) {
}The second option is to keep a reference to the MainCanvas instance in SubCanvas, and use this reference to call your own callback function:
class SubCanvas extends Canvas {
  MainCanvas mc
  public SubCanvas(MainCanvas mc) {
    this.mc = mc
  void keyPressed(int keyCode) {
    if (keyCode == theKeyThatCallsMainCanvas) {
      mc.callbackFunction();
class MainCanvas extends Canvas {
  public void callbackFunction() {
}shmoove