android - Save and restore instance state of an Activity manually -

i have download activity in app, users can download content. activity called main activity, , retrieves list of available files download on network.

to avoid fetching whole list again when download activity recreated e.g. because of rotation, override onsaveinstancestate() store list in bundle , evaluate bundle passed oncreate() method. works rotation.

however, able implement same behavior if user hits , later returns download activity. android in case not call onsaveinstancestate(), hence nothing gets saved.

my idea override onbackpressed() , include call onsaveinstancestate().

• will work @ all?
• can onsaveinstancestate(new bundle()), or have initialize new bundle somehow?
• will android store bundle , pass oncreate() next instance of activity creates, or have take care myself of storing bundle , passing new instance (if so, how)?

update:

simply adding

@override public void onbackpressed() {     onsaveinstancestate(new bundle());     super.onbackpressed(); } 

gives me following exception:

java.lang.illegalstateexception: can not perform action after onsaveinstancestate

for call onbackpressed(). (swapping 2 lines nothing, presumably because there nothing left save.)

will work @ all?

no.

will android store bundle , pass oncreate() next instance of activity creates

no.

do have take care myself of storing bundle , passing new instance (if so, how)?

no.

store model data in file or database, process-level cache (e.g., custom singleton) minimize disk i/o. load data out of cache available, or reload disk if needed.