Android会阻止恢复活动

Question

I have a viewpager holding many fragments. When the activity is sent to background and when resources are needed, the OS will kill the app or at least some fragments. When I return to the activity it crashes because the activity tries to attach new instances of all fragments it held before the clean-up and now some fields are null. This of course could be fixed by properly implementing state saving and restoring using Bundles, but I don't want to do that. Instead I want to prevent restoring the fragments. Is there a way to tell the OS that once it has sent the GC in and destroyed fragments, it shouldn't bother recreating them at all? Once the cleaning-up happens, I want the activity to be simply recreated on return, as if a user launched it by taping the icon. Any chance of doing that?

The proposed solution here https://stackoverflow.com/a/15683289/552735 does not work. It causes exceptions java.lang.IllegalStateException: Fragement no longer exists for key f2: index 3

Answer 1

I had a problem just like this. Here's how I fixed it:

    @Override 
    protected void onSaveInstanceState(Bundle savedInstanceState)
    {
        savedInstanceState.clear();
    }

Note that this method will ensure that absolutely no UI state information will be stored when the Activity is killed by the system - this has the effect of also not restoring any Views when onRestoreInstanceState() gets called with the same Bundle after onStart() .

Answer 2

You can't disable the save/restore instance state actions. In case you don't want to actually implement this logic, you have to reload the form especially if your form heavily loaded with fragments.

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
     startActivity(new Intent(this,YOUR_ACTIVITY.class));
     finish();
}