You can use this method to trigger something when the home or "up/back" button in the actionbar is pressed.
For example, save what the user is currently doing or writing.
You can listen for the Home button pressed event in the optionsItemsSelected method:
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home: {
doSomething();
return true;
}
}
return super.onOptionsItemSelected(item);
}
Returning true after executing your method, "consumes" the event, so it does not propagate further.
More information on Actionbar home button, and optionItemsSelected can be found here and here.