重新打开和替换片段时Android应用程序崩溃

Question

For my current application that I'm writing I have implemented a navigation drawer (the default Android way with backwards compatibility). So from the nav drawer you select a menu element and then I do this (addPreviousToBackStack is always false for testing):

private void replaceFragment(final Fragment fragment, final boolean addPreviousToBackStack) {
    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    fragmentTransaction.replace(R.id.activity_main_fragment_container, fragment);
    if(addPreviousToBackStack) {
        fragmentTransaction.addToBackStack(fragment.getTag());
    }
    fragmentTransaction.commit();
    currentFragment = fragment;
}

So that works like a charm when I start the application. Then I close the application using the back button. If I then reopen the app (no matter how: via the long press home button or via the shortcut) the app starts at the initial screen (onCreate is called) and then I open the nav drawer and select a menu item and the application crashes.

This is my exception: "java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState"

And it happens exactly on my line where I do

fragmentTransaction.commit();

I have no clue why I'm getting this when the app is re-opened and not when the app is initially opened. Any clues??

Answer 1

I am not sure what is the context of your use case, but calling fragmentTransaction.commitAllowStateLoss(); should not cause the crash anymore. However, you need to assume the risk that your state info will be lost on fragment.

Also, this line currentFragment = fragment; seems to me a cause of memory leak. If Android wants to cleanup the fragment you will prevent it by keeping a strong reference to the fragment. Don't use it ...