This is not my code. I just arrived at this site and am doing code review.
They have a class which is an extension of Dialog.
It has been defined as a singleton.
On the first call the context is passed to the getInstance method.
It instantiates the class passing the received context to the “super” within the constructor.
Then it saves it – same as in any singleton.
It then displays the dialog. After user interaction it starts a new activity and closes the dialog via “closeDialog”.
However, it is still alive since the static holder for the instance is still there.
Will this then hold on to the activity that created it (and was passed on the “getInstance” call and into the “super()” when creating the instance)?
They keep the instance alive because they then use it for calls from other places and have values that need to be carried over.
I know this code stinks but I want to be sure that it does leak memory (the first activity) before I make them re-write it (or re-write it myself – which is more likely).
Yes it could. If the code starts other activities, then yes. If only the one activity is ever used, then most likely not. The reason being, dialogs must be instantiated with an activities context (it’ll crash with the Application context). If that activity is set to be destroyed, garbage collection won’t clean it up until all references to it are destroyed. If this singleton dialog lives outside the activity (which should be the case), then it’ll continue referencing the activity and prevent GC from cleaning it up. You can read more about leaking contexts here: Avoiding memory leaks
As you stated the code is bad, and using a singleton dialog like that is just plain wrong (whether it leaks or not). There are better ways of maintaining data between states.