Develop Reference

How to execute code when Home button is pressed?

I want to run code only when the home button (when the app is sent to background) is pressed. I tried using the lifecycle-method but the problem is that they also get executed when and other dialog/activity is started. I only want to check if the application is sent to background. How can I achieve that?

In onOptionsItemSelected(MenuItem item);, check to see if the item clicked is the home button:
EDIT:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
finish();
return true;
}
return super.onOptionsItemSelected(item);
}

Activity.onUserLeaveHint() fires on your activity when the Activity is going to be backgrounded as a result of user action, such as pressing the home button or switching apps.

Well since you are writing the code you can set some boolean flags when you start explicitly another acitivty, and check that when your activity goes through onPause()...
if they are false, it means someone else is pausing your activity.
Maybe not the most elegant solution but it will work if that is the only problem you have.

You could have a tracking system (basically a counter) to know when one of your activities is resumed and paused, thus allowing you to know if any of your activities is open.
This way you could know if your app is "open". but this would not apply only to the home button, but to the back button (last back to close your app) or even opening another app from the notification bar.

Android OS will kill your application to free resources, it wont stay in the background all the time. Use service if you want your app keep running in the background

If you want to do when the home button is pressed and the activity is going background, you can override this on the activity:
#Override
public boolean onKeyUp(int keyCode, KeyEvent event)
{
switch(keyCode)
{
case KeyEvent.KEYCODE_HOME:
//somthing you want to do
default:
return super.onKeyUp(keyCode, event);
}
}
I am using the KeyUp event because that's when the app goes backgroud, the user can do a longPress and I don't think you want to do the method when the app still open.

this is sort of a cheat answer, but i find it to be much more reliable.
one method that's always called when you press the home button is the surfacedestroyed method for any surfaceviews contained in any of the program's activities.
Putting the code you want to execute there, having the method point to another method you want to execute, or having the method trigger a flag that points to the method you want to execute will do the job.

In my own custom android home screen, how do I catch the home button?

I know that android does not allow us to catch the home button press; however, I have my own built home screen replacement app and want to just know when the button was pressed to allow animations.
So, my app has just one activity as I do most of my "activities" as canvas drawing so I can have complete control over the visual aesthetics of my app. The problem is if the user navigates to a different page within the app and presses home, nothing happens, since the app is technically already in the same activity.
I want to know when the button is pressed so I can then animate/navigate my app back to the main screen. Also, I know I could accomplish this by having separate real activities however that won't work for what I'm trying to do.

You need to add <category android:name="android.intent.category.HOME"/> to your activity's intent filter in your app's Android.xml
You can take a look at "Home" app in Android SDK samples. They can be downloaded using these instructions.

//overriding method
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_HOME)
{
//The Code Want to Perform.
}
});

You can detect when the home button is pressed because onPause() is always called. You are not allowed to override the home button, but the following should work
#Override
protected void onPause()
{
super.onPause();
//code here
}
Of course the problem with using this is that it will be called even if the user is not quitting the app(ie. If they are sent to another application through an intent)
That is the closest that you are going to get to a onHomeButtonPressedListener there are really no ways to do this
Home key press Event Listener

Starting an Activity from a service and do not want any key input

I'm starting an activity from a service, which displays some text.
Now if a user presses a key - say a back key, I would like that back button to be processed by any other app which may be running (not started by my service).
Is this possible? I have tried FLAG_NOT_FOCUSABLE, however, the back key is still not processed by any other app/ignored. Android, after some time keep giving a option for "Force Close" or 'Wait".
Any pointers will be helpful.
Just FYI, "whitepages" app does something like this - it shows a dialog window, however, doesn't process the back key.
Thanks.

I'm not sure if this is correct or not, but I've seen the same behavior in a few apps myself. I think they are using Toast messages to display the text. I'm not sure if a service can display Toast or not - you'll have to try... if not then you could also try having the Activity display the toast and immediately exit.

Only the currently running activity receives in the button pressed signal. All you can do is intercept the back button press by implementing:
onBackPressed()
On older devices this won't quite work and you'll need to do something like:
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (keyCode == KeyEvent.KEYCODE_BACK) {
//Do something here
return true;
}
return super.onKeyDown(keyCode, event);
}
As far as passing the button press to another activity, I'm not sure you can do that. What you could do is pass the activity an intent that could specify the back button was pressed. However, this assumes that the other activity is setup to deal with such an intent.

How-to Keep an Android Activity Running when hitting the back key

I have an activity that essentially launches a CountDownTimer. I need this to continue running while using other Android apps, such as Gmail, and media players etc.
When I hit the back button, my Activity seems to quit. What do I need to do to keep it running when the user clicks the back/home keys etc.

You have to use a Service, you can read the documentation here.

Activities are not supposed to be doing anything when they are not visible. They are basically UI components.
You should be looking into services. These can run as a background process nd contain no UI.

It's been referred to as a serious "hack" by a few developers, but I've successfully checked for the back button being pressed so as to successfully clean my project up. I've recently moved most of this code to onPause() event because it's called right before the app goes down after back button is pressed. However, if it's really what you desire, it's your program and here's the code I used:
if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
killAndReturnParams(0);
}
Again, this method has been talked down before, but I'm pretty sure it's because you're not supposed to override the back button for any reason. The user is supposed to be able to use the back button to return at any point, in any app.

#Override
public void onBackPressed() {
mActivity.moveTaskToBack(true);
}

BadTokenException - BACK button

I know this topic was asked trillions of times throughout the web, but there is no one place answering it.
in my application, I have a welcome screen. when I run the program end-to-end everything is just fine - open/close activities and show dialogs of all sorts.
but, when I reach the welcome screen and from there pressing the BACK button - everything becomes messy:
1) the dialog i want to show cause BadTokenException (i'm using this and not getApplicationContext() ).
2) I tried use try/catch to catch the exception - and it really passed the showDialog line. but then, in the 2nd. run, when reaching a showDialog expression, it throws IllegalStateException: View.com.android.internal.policy.impl.PhoneWindow$DecorView#44a59830 has already been added to the window manager.
moreover, I understand that pressing HOME causes the onPause in the activity, while BACK causes onDestroy, but what goes wrong ??
i'm trying to fix that issue for more than a week, but with no success.
any ideas ?

I didn't get you complete, But i think you need to do some stuff when you back button is pressed. So you can override you back button in you welcome screen activity or any other activity and add you code there
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
// add you code here
return true;
}
return super.onKeyDown(keyCode, event);
}