Develop Reference

Handle keyboard navigation arrows

On a Samsung Tablet, we have the following keyboard:
When a clic occurred on the right bottom arrows, in the view pager, fragment is changed. I want to intercept this event or remove the arrows from the keyboard. Is it possible ?
I tried to intercept keyevent with onKeyUp and onKeyDown methods, but it's not working:
if (event.getKeyCode() == KeyEvent.KEYCODE_DPAD_RIGHT || event.getKeyCode() == KeyEvent.KEYCODE_DPAD_LEFT) {
return true;
}
My problem is the same as here

Try to use dispatchKeyEvent(KeyEvent event):
#Override
public boolean dispatchKeyEvent(KeyEvent event) {
Log.i("key pressed ", String.valueOf(event.getKeyCode()));
if(event.getKeyCode() == KeyEvent.KEY_A /*select required keycode*/ ){
// perform task
}
return super.dispatchKeyEvent(event);
}

close android app with down botton

I have a problem with the back button event and a code to close my app. I explain:
I have an app with two activities. The first activity displays a list of events in a listview. When you click on one of these events a new activity that can confirm attendance at the selected event opens. If this second activity you press the button that confirms attendance returns to the main activity.
My problem is that if once you hold an event from the main activity and confirm second activity giving the button that returns you to the main activity when the main activity to give back button instead of closing the app returns to the second activity.
Therefore I want to record the event of pressing the button back and close the app, I tested with:
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
android.os.Process.killProcess(android.os.Process.myPid());
return true;
}
return super.onKeyDown(keyCode, event);
}
and too:
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
exit(0);
return true;
}
return super.onKeyDown(keyCode, event);
}
thank you very much for your time and help
ANSWER
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
Intent homeIntent = new Intent(Intent.ACTION_MAIN);
homeIntent.addCategory( Intent.CATEGORY_HOME );
homeIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(homeIntent);
return true;
}
return super.onKeyDown(keyCode, event);
}

I think you have set up the activities wrong. You should set a result in the second activity, and then call it's finish() method. Then the back button will always work as expected and you won't have to do weird hacks like that.

android : how could I exit the app?

In my android application I changed the back button functionality so that it goes to the main screen of my game , now that it's on the main screen how should I exit the whole application with back button ?
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK ) {
Assets.getInstance().getClick().play(1);
this.clearScreenStack();
this.setScreen(new MainMenuScreen(this));
return true;
}
return super.onKeyDown(keyCode, event);
}

If you have a mechanism that you can use to see which screen is showing you could do something like this:
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK ) {
if(mainScreenIsShowing == true){
//If the main screen is showing let the back button
//have its default behavior.
return super.onKeyDown(keyCode, event);
}else{
Assets.getInstance().getClick().play(1);
this.clearScreenStack();
this.setScreen(new MainMenuScreen(this));
return true;
}
}
return super.onKeyDown(keyCode, event);
}

You can also check if the user enters the back button two times.
boolean backPressed = false;
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && !backPressed) {
Assets.getInstance().getClick().play(1);
this.clearScreenStack();
this.setScreen(new MainMenuScreen(this));
backPressed = true;
return true;
}
backPressed = false;
return super.onKeyDown(keyCode, event);
}

This is a debateable subject, but I see nothing wrong or with an application exiting when the back button is pressed. After all, a call to finish() is the default behaviour of the back button. If the activity handling your main screen is at the bottom of your activity stack, then a call to finish() will exit your application.
I propose the following: Let your MainMenuScreen be handled in a separate activity, MainMenuActivity, which is the main activity. finish() other activities when going back to the MainMenuActivity, and handle onKeyDown like this in MainMenuActivity:
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK ) {
this.finish()
}
}

How to access menu button onLongClick in Android?

How can I set a listener for long-click performed on hardware Menu button? What is the way of programmatic access to the Menu button?
Moreover how can I distinguish long-click from single-click? (As far as I know when long-click is performed the single-click event is propagated as well - I do not want this to happen because I need 2 different actions for these 2 situations. Long-click and single-click separate listeners for the device Menu button)
Thank you!

This shoule be fairly straight forward. Check out the KeyEvent.Callback on the Android developer's website.
There you will find onKeyLongPress() as well as onKeyDown() and onKeyUp(). This should get you on the right track. Comment or post you code if you need any further help.
Edit: I just re-read the question. If you are having trouble distinguishing single click from long click, you will need to use onKeyDown and onKeyUp and check the duration of the click. Esentially you will start a timer in the onKeyDown and check the time in the onKeyUp. You will have to watch for FLAG_CANCELED.
Further Edit: I found the time to do a couple of tests. This code should do what you want (onKeyUp() gets only short press events and onLongPress() gets only long press events).
The key thing here is in the call to event.startTracking() in the onKeyDown() handler.
Place in Activity (this should also work in a custom view as well but untested):
#Override
public boolean onKeyLongPress(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_MENU) {
// Handle Long Press here
Log.i("KeyCheck", "LongPress");
return true;
}
return super.onKeyLongPress(keyCode, event);
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
Log.i("KeyCheck", "KeyDown" + keyCode);
if (keyCode == KeyEvent.KEYCODE_MENU) {
event.startTracking(); //call startTracking() to get LongPress event
return true;
}
return super.onKeyDown(keyCode, event);
}
#Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_MENU && event.isTracking()
&& !event.isCanceled()) {
// handle regular key press here
Log.i("KeyCheck", "KeyUp");
return true;
}
return super.onKeyUp(keyCode, event);
}

Android Home button click ignoring saved state?

Can I ignore the previous stage of application after tapping Home button in android?
So that I can get the application from initial screen.

Use like this.If now you are in LastActivity and you want to go back to the First Activity and there is more activity in between then if you want to go first from last use
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(autoSearch)
if (keyCode == KeyEvent.KEYCODE_HOME) {
Log.d("click","HOMEButtonclicked");
LastActivity.this.startActivity(new Intent(LastActivity.this, FirstActivity.class));
moveTaskToBack(false);
return true;
}
return super.onKeyDown(keyCode, event);
}