How do I kill an Activity when the Back button is pressed

Question

I got an Activity that when it starts  it loads an image from the internet  In an effort to save memory  when the Activity is left by the back button being pressed  I want the activity to dump all data  that is get rid of all the strings and images that are in it  I figured the best way to do this was to just kill the activity    Well  I can t seem to figure out the callback for when the Back button is pressed  So  I have been trying to use the onPause   and the onStop   callbacks for the task but both ways force close my app  Here is the code   public void onPause         this finish      public void onStop         finish        I ve tried multiple variations of this  but none of them seemed to work  Any ideas

User · Answer

First of all  finish   doesn t destroy your process and free up the memory  It just removes the activity from the activity stack  You d need to kill the process  which is answered in a bunch of questions  since this is being asked several times    But the proper answer is - Don t do it  the Android OS will automatically free up memory when it needs memory  By not freeing up memory  your app will start up faster if the user gets back to it   Please see here for a great write-up on the topic

User · Answer

add this to your activity   Override public boolean onKeyDown int keyCode  KeyEvent event        if   keyCode    KeyEvent KEYCODE BACK                 finish              return super onKeyDown keyCode  event

User · Answer

Simple Override onBackPressed Method        Override     public void onBackPressed                 super onBackPressed                this finish

User · Answer

Well  if you study the structure of how the application life-cycle works here   then you ll come to know that onPause   is called when another activity gains focus  and onStop   is called when the activity is no longer visible   From what I have learned yet  you can call finish   only from the activity which is active and or has the focus  If you re calling finish   from the onPause   method that means you re calling it when the activity is no longer active  thus an exception is thrown   When you re calling finish   from onStop   then the activity is being sent to background  thus will no longer be visible  then this exception   When you press the back button  onStop   is called   Most probably  Android will automatically do for you what you are currently wanting to do

User · Answer

public boolean onKeyDown int keycode  KeyEvent event        if  keycode    KeyEvent KEYCODE BACK            moveTaskToBack true             return super onKeyDown keycode  event       My app closed with above code

[android] How do I kill an Activity when the Back button is pressed?

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