有什么方法可以调用清理函数，该函数还清理本机代码，同时在Android中保留任何活动？

Question

see

i have mainActivity which calls tempActivity

Now inside tempActivity i call some native method and malloc some data .. so now when user

1> come back from tempActivity to mainActivity or

2> exit from whole application

i need to call one clean up function which free all data malloc in native method so how can i implement such things?

Does android framework has any method to handle such clean up function?

Answer 1

Ok, i think the question is about how to free the memory that is being allocated using malloc() inside native code.

I had the same requirement in one of my Projects. I did it in the following way.

Inside onStop() or onDestroy() , I did a native call, which I have used to free() the allocated memory. This I think is the best and simplest way to do that. I am not sure if android is providing some API,s for this. It would be informatory to know if something like this exists. Thanks.

Answer 2

See the diagram taken from here .

Basically the Activity class is defining several methods that can be of use to you:

• onPause which is called every time your activity is paused: that is your screen locks, you go to other activity
• onDestroy and onStop called when you go to other activity.

Maybe some of these methods will be useful for you.

Answer 3

1. For the transition from tempActivity to mainActivity , put a call to the clean up function in tempActivity 's onDestroy method.
2. For the case where the entire application is exited: that is much more messy. There is no global function that tells when an app exits, so you'll need to use some other means of tracking that the application is exiting.

I'd recommend using a Service with the onStartCommand function set to use START_NOT_STICKY and then in the onDestroy method of the Service call the clean up function. If you do this and you have all Activity s use the service then you can do it all in there.

Answer 4

The recommended technique is to allocate whatever you need in onResume and clean up in onPause . This way you allocate when your activity is about to be shown and clean up when your activity has become partially or fully obscured by some other activity.