cannot close the screen in blackberry - blackberry

Question

I am using finish() to close current activity before quit application in Android.
However, I cannot close screen in blackberry.
public class Main_AllLatestNews extends MainScreen {
public Main_AllLatestNews() {
super(USE_ALL_WIDTH);
}
private boolean Dialog() {
final Bitmap logo = Bitmap.getBitmapResource("icon.png");
d = new Dialog("确定离开？", new String[] { "是", "否" }, new int[] {
Dialog.OK, Dialog.CANCEL }, Dialog.OK,
logo) {
public void setChangeListener(FieldChangeListener listener) {
if (d.getSelectedValue() == Dialog.OK) {
} else {
d.close();
}
};
};
d.show();
return (d.doModal() == Dialog.OK);
}
public boolean onClose(){
if(Dialog()){
System.exit(0);
return true;
}else
return false;
}
}
Here is my Main class
public class Main extends UiApplication {
public static void main(String[] args) {
Main theApp = new Main();
theApp.enterEventDispatcher();
}
public Main() {
pushScreen(new MyScreen());
}
public final class MyScreen extends MainScreen {
private Bitmap logo = Bitmap.getBitmapResource("logo_page.png");
private BitmapField bmfield;
public MyScreen() {
setTitle("Oriental Daily");
bmfield = new BitmapField(logo, Field.FIELD_HCENTER
| BitmapField.FOCUSABLE) {
protected boolean navigationClick(int status, int time) {
Main.this.pushScreen(new Main_AllLatestNews());
Main.this.popScreen(MyScreen.this);
return true;
}
};
}
}

Answer 1

It depends on exactly how you want your close behaviour to work. Also, I can only read English, so I'm not 100% sure what your Dialog says. I'm assuming it's something to do with closing the app (yes or no)?
Anyway, usually, my apps close by overriding the onClose() method in the MainScreen subclass. You don't actually need to listen for the escape key. onClose() will get called normally when the user escapes all the way out of the app, or presses the little button with the blackberry icon, and then selects Close.
public final class MyScreen extends MainScreen {
/** #return true if the user chooses to close the app */
private boolean showDialog() {
Bitmap logo = Bitmap.getBitmapResource("icon.png");
Dialog d = new Dialog("确定离开？",
new String[] { "是", "否" },
new int[] { Dialog.OK, Dialog.CANCEL },
Dialog.OK,
logo);
return (d.doModal() == Dialog.OK);
}
/** Shutdown the app? */
public boolean onClose() {
if (showDialog()) {
System.exit(0);
return true;
} else {
// the user does not want to exit yet
return false;
}
}
}