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How to quit another application (not mine) from my app's service but not killing it

I am working on an app service that will display on top of another app that is currently on the foreground and if the user pressed on the back button it will destroy the service and exit the app too, but not killing it.
I had read many articles on stack overflow that tells me to use finish() or finishAffinity() but it only works if it is my own app activity.
Can I exit the app with its package name?
FrameLayout interceptorLayout = new FrameLayout(this) {
#Override
public boolean dispatchKeyEvent(KeyEvent event) {
// Only fire on the ACTION_DOWN event, or you'll get two events (one for _DOWN, one for _UP)
if (event.getAction() == KeyEvent.ACTION_DOWN) {
// Check if the HOME button is pressed
if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
Log.v(TAG, "BACK Button Pressed");
onDestroy();
// As we've taken action, we'll return true to prevent other apps from consuming the event as well
return true;
}
}
// Otherwise don't intercept the event
return super.dispatchKeyEvent(event);
}
};

I am not recommending to close other app.
You can exit with other app's package name
Declare a permission for that in your AndroidManifest.xml file. here it is :
<uses-permission android:name="android.permission.KILL_BACKGROUND_PROCESSES" />
and now use ActivityManager class to kill other apps and it will work.
ActivityManager am = (ActivityManager)getSystemService(Activity.ACTIVITY_SERVICE);
am.killBackgroundProcesses(packageName);

Check if activity is visible (onResume&Pause dosen't suit, because of multiwindow mode)

I need to ensure somehow the activity is on screen visible to user eyes.
We can do this by listetning to onResume & onPause events in Activity class and setting some boolean in these functions.
But onPause is called not only when you minimize your activity, onPause is also called when you switched to other window in multiwindow mode (Android 7.x Nougat)
So the boolean onPause&onResume method will lead to mistakes.
Then how to know visibility of Activity?
Thanks for help.

On Nougat and above you must check the onStop method , it will tell you when your Activity is not visible , you could use this code:
#Override
public void onPause() {
super.onPause();
if (Build.VERSION..SDK_INT <= 23) {
//your activity is not visible
onHidden();
}
}
#Override
public void onStop() {
super.onStop();
if (Build.VERSION..SDK_INT > 23) {
//your activity is not visible
onHidden();
}
}
Assuming that your onHidden method will perform some action.
I found this interesting link about your problem: Multiwindow

Android back button forcing app restart and not resuming properly

In my app my first activity to launch is a login activity (A). When the login is successful another activity is launched (B), in doing so activity A is killed using finish(). This is to prevent the user being taken back to the login screen if they hit the back button, which works fine. Now when the app is closed from activity B using the home button and restored from the multitasking view the user comes back to activity B, which is great. However, when the user taps the back button in activity B the app closes and when the app is restored from the multitasking view, activity A is launched again when I actually want the behaviour clicking the home button gives and presenting the user with activity B.
Is there any way to do this?

You should simply add a check to your login activity, if the user is already signed in finish it and launch your B activity.

I'm really silly, just found my answer in one of the 'related' questions but it didn't come up when I created my question, oh well.
Here's what I did:
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK
&& event.getRepeatCount() == 0) {
Log.d("CDA", "onKeyDown Called");
onBackPressed();
return true;
}
return super.onKeyDown(keyCode, event);
}
#Override
public void onBackPressed() {
Log.d("CDA", "onBackPressed Called");
Intent setIntent = new Intent(Intent.ACTION_MAIN);
setIntent.addCategory(Intent.CATEGORY_HOME);
setIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(setIntent);
}
This essentially emulates what the home button would do in activity B.

Android backround music across multiple activities; How to catch Home button presses

I want to play an audio file in the background of my app. Easy enough. I want the music to persist and NOT stop or pause while switching between activities in my app. Also fairly easy and accomplished simply by doing this in the onCreate method:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
...
mp = MediaPlayer.create(MainActivity.this, R.raw.lostmexicancity);
mp.setLooping(true);
mp.start();
}
The problem? Getting the music to stop when I press the HOME button.
Killing the sound when the user presses the back button seems easy. Here's what I have for that and works great:
public void onPause() {
if(this.isFinishing()){ //BACK was pressed from this activity
mp.stop();
}
super.onPause(); }
Not complicated, but this does not catch presses of the HOME button. If the Home button is pressed, the music keeps playing even while the user no longer sees my app.
I have seen answers that involve setting permission in the manifest to Get Tasks which I shouldn't have to do and appears dangerous to users. Besides that, the solution didn't even work. I've seen solutions that involve using a service, but none of those work either because the home button STILL plays the music just like before because there doesn't seem to be a way to catch it and it doesn't 'finish' the app (not to mention that every time someone suggest using a service for this task multiple people come in and state that this is not a proper use for services)
It seems the only way to kill the music when the Home button is pressed is to use a non-conditional stop() within onPause, but that's no good because that's called when I swap activities with intents, causing the music to end between activities which is no good.
I have trouble imagining that such a common function like background music is this hard, but I've seen post after post with the same issue as me and no proper answers other than ones that would kill the music between activities within the app.
How do all the other apps on the Google play store accomplish this and yet there appears to be no clear answer online? I could just stop and start the music with each onPause(), but that would cause unprofessional gaps in audio not to mention it would start the background audio from the beginning over and over again which is unacceptable.

I'm a bit new to Android Programming (few months) and today, I faced the same problem you did (maybe you still do?)
I made it work as the following :
Lets say I have MainActivity, and in MainActivity I have Btn2 which leads to SecondActivity, and Btn3 which leads to ThirdActivity.
I declared at the beginning of MainActivity :
public static boolean shouldPlay = false;
I then implemented my onStop() method :
public void onStop() {
super.onStop();
if (!shouldPlay) { // it won't pause music if shouldPlay is true
player.pause();
player = null;
}
}
If the boolean shouldPlay is set to true, then my onStop() won't be called entirely and my music won't turn off. I then have to decide when I set it to true. When I switch from MainActivity to SecondActivity, I do it through an Intent and that's when I'll set shouldPlay to true :
Button Btn2 = (Button) findViewById(R.id.Btn2);
Btn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
shouldPlay = true;
startActivity(intent);
}
});
And the same is done for Btn3.
Now, the last thing we want to be looking for is that if I was to go back to MainActivity after visiting SecondActivity or ThirdActivity, shouldPlay would then have been set to true. The first thing I tried was to set it to false as soon as Second and ThirdActivity are called (in their onCreate()) but it want to work, maybe because the onStop() from Main and onCreate() from others are called simultaneously (frankly I don't really get life cycle for now).
What worked is simply to set shouldPlay to false every time we launch onCreate() of Main :
shouldPlay = false;
This works properly for me.
Let me know if it does for you,
Cheers,
bRo.

#Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if(keyCode == KeyEvent.KEYCODE_HOME){
Log.d("Jorgesys", "Home button pressed!!!");
}
return super.onKeyDown(keyCode, event);
}
but hey! This no longer works as of 4.0 + , Read this: Capture Home Key Event
Try with Back button:
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK ) {
Log.d("Jorgesys", "Back button pressed!!!");
}
return super.onKeyDown(keyCode, event);
}
To stop the media player, you are using the method:
isFinishing(): if the activity is finishing, returns true; else
returns false, but you are only pausing the activity not finishing the
activity.
public void onPause() {
if(this.isFinishing()){ //INCORRECT, Here you are pausing you activity not finishing.
mp.stop();
}
super.onPause();
}
so change to:
public void onPause() {
if(mp.isPlaying())
{
mp.stop();
}
super.onPause();
}
When your activity is on pause, evaluates if your MediaPlayer is playing, if this is true then stops the audio.

How can I use the Android back button to move back within my app instead of closing my app?

My app has three activities, A, B and C. I am moving from A to B through an OK button, and I want to move back from B to A by using the default back button of Android devices. When I press the button, though, the entire app gets closed. How can I get around this problem?

I suspect you call finish() in your OK button onclick listener. Don't do that. finish() removes your activity from activity stack.
Read more here.

why start your activity for result ? when you press the backbutton, the result is set to RESULT_CANCELED form the B activity, so it crashes if you don't handle the resultcode...
you can handle the backpress like this
private static final int NONE = -1;
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
setResult(NONE, intent);
finish();
return super.onKeyDown(keyCode, event);
}

When you are Ok button r u starting an intent...like
Intent int=new intent(context,B.class);
startActivity(int);
then if you are not handling backbutton.
If use default back button...it will goes back to A.
Hope it helps...

In my onClick method (in Main Activity) I use the code:
Intent intent = new Intent(context, SecondActivity.class);
context.startActivityForResult(intent, SecondActivity.SECONDACTIVITY_REQUEST);
In the manifest I've got:
<activity android:name=".SecondActivity" android:screenOrientation="landscape" android:launchMode="standard"></activity>
This works for me without any other settings that I can see. What events are you responding to?
Note that you can also go back an activity, in code like this:
super.setResult(Activity.RESULT_OK);
super.finish();
Edit...
Make sure you're not swallowing the event in the Main Activitys onKeyDown event.
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
//your code here
//if (keyCode ==
//...
//else
return super.onKeyDown(keyCode, event);
}