Trying to detect ActionMode memory leak

Question

I have been trying to find the source of ActionMode memory leak for days now without luck. I have an activity with several fragments and when I leave the fragment having ActionMode (while auto cancelling it), LeakCanary detects a memory leak.

I have nulled both ActionMode and ActionMode.Callback on destroy() and even tried doing it on onDestroyActionMode().

Here is my LeakCanary screenshot:

https://i.imgur.com/RUbdqj3.png

I hope someone points me in the right direction.

P.S. I have suspected it has something to do with ActionMode.Callback. Though, I could not find any methods for the CallBack that destroys it. I start the ActionMode using startSupportActionMode(mActionModeCallback). I have tried to find a method to remove the mActionModeCallback from that, too, but no methods.

Here is my full ActionMode code:

private ActionMode mActionMode;
private ActionMode.Callback mActionModeCallback;

public void startCAB()
{
    if (mActionMode == null)
        mActionMode = ((AppCompatActivity) getActivity()).startSupportActionMode(mActionModeCallback);
}


private void buildActionModeCallBack()
{
    mActionModeCallback = new ActionMode.Callback() {
        @Override
        public boolean onCreateActionMode(ActionMode mode, Menu menu) {
            MenuInflater inflater = mode.getMenuInflater();
            inflater.inflate(R.menu.menu_cab, menu);
            return true;
        }

        @Override
        public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
            return false;
        }

        @Override
        public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
            switch (item.getItemId()) {
                ... Some Code ...
            }
        }

        @Override
        public void onDestroyActionMode(ActionMode mode) {
            mActionMode = null;
    mActionModeCallback = null; // Tried with and without this.
        }
    };
}

public void finishActionMode()
{
    mActionMode.finish();
}

@Override
public void onDestroy()
{
    super.onDestroy();
    mActionMode = null;
    mActionModeCallback = null;
}

Parent Activity containing fragments:

@Override
public void onTabUnselected(TabLayout.Tab tab)
{
    clearCAB();
}

private void clearCAB()
{
    int index = mPagerAdapter.getCurrentFragmentIndex();
    FragmentOne fragmentOne = (FragmentOne) mPagerAdapter.instantiateItem(mViewPager, index);
    fragmentOne.finishActionMode();
}

Answer 1

According to my experience, if your ActionMode.Callback object use the Anonymous inner class it may cause your fragment memory leak.

Maybe you can create a new class and implements ActionMode.Callback then use it to put in startSupportActionMode() parameter:

public class YourFragment extends skip implements skip, ActionMode.Callback {

    private ActionMode mActionMode;

    public void startCAB()
    {
        if (mActionMode == null)
            mActionMode = ((AppCompatActivity) getActivity()).startSupportActionMode(new SafeActionModeCallback(this));
    }

    public void finishActionMode()
    {
        mActionMode.finish();
    }

    @Override
    public boolean onCreateActionMode(ActionMode mode, Menu menu) {
        MenuInflater inflater = mode.getMenuInflater();
        inflater.inflate(R.menu.menu_cab, menu);
        return true;
    }

    @Override
    public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
        return false;
    }

    @Override
    public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
        switch (item.getItemId()) {
            // ... Some Code ...
        }
    }

    @Override
    public void onDestroyActionMode(ActionMode mode) {
        mActionMode = null;
    }
}

SafeActionModeCallback:

public class SafeActionModeCallback implements ActionMode.Callback {

    // you can also use the WeakReference
    private ActionMode.Callback callback;

    public SafeActionModeCallback(ActionMode.Callback callback) {
        this.callback = callback;
    }

    @Override
    public boolean onCreateActionMode(ActionMode mode, Menu menu) {
        return callback.onCreateActionMode(mode, menu);
    }

    @Override
    public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
        return callback.onPrepareActionMode(mode, menu);
    }

    @Override
    public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
        return callback.onActionItemClicked(mode, item);
    }

    @Override
    public void onDestroyActionMode(ActionMode mode) {
        callback.onDestroyActionMode(mode);
        callback = null;
    }
}