Android: AbsListView.setItemChecked() cause ActionMode Destroy and Recreate?

Question

If you call AbsListView.setItemChecked() directly, it works well, and the ActionMode will activate and create.

mGridView.setItemChecked(pPosition, true);

But when you call View.startActionMode() first, then call AbsListView.setItemChecked(), the ActionMode create by startActionMode() will destroy, and recreate a new one by setItemChecked().

My question is: How to avoid this issue when call View.startActionMode() first?

Looking forward to your reply! Thanks!

Answer 1

Why recreate a new one? See the source code of AbsListView.setItemChecked(int position, boolean value) method, you can see following code：

    // Start selection mode if needed. We don't need to if we're unchecking something.
    if (value && mChoiceMode == CHOICE_MODE_MULTIPLE_MODAL && mChoiceActionMode == null) {
        if (mMultiChoiceModeCallback == null ||
                !mMultiChoiceModeCallback.hasWrappedCallback()) {
            throw new IllegalStateException("AbsListView: attempted to start selection mode " +
                    "for CHOICE_MODE_MULTIPLE_MODAL but no choice mode callback was " +
                    "supplied. Call setMultiChoiceModeListener to set a callback.");
        }
        mChoiceActionMode = startActionMode(mMultiChoiceModeCallback);
    }

That means if mChoiceActionMode == null, it will call startActionMode(mMultiChoiceModeCallback), so will recreate a new ActionMode.

And how to fix? Here is a simple way: use reflect to assign a ActionMode create by startActionMode() to the private field mChoiceActionMode in AbsListView.

private void startActionMode() {
    // Get the field "mMultiChoiceModeCallback" instance by reflect
    AbsListView.MultiChoiceModeListener wrapperIns = null;
    try {
        Field wrapper = null;
        wrapper = AbsListView.class.getDeclaredField("mMultiChoiceModeCallback");
        wrapper.setAccessible(true);
        wrapperIns = (AbsListView.MultiChoiceModeListener) wrapper.get(mMessageGridView);
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    }
    // Start the ActionMode, but not select any item. 
    ActionMode actionMode = mMessageGridView.startActionMode(wrapperIns);
    // Assign actionMode to field "mChoiceActionMode" by reflect 
    try {
        Field mChoiceActionMode = null;
        mChoiceActionMode = AbsListView.class.getDeclaredField("mChoiceActionMode");
        mChoiceActionMode.setAccessible(true);
        mChoiceActionMode.set(mMessageGridView, actionMode);
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    }
}

Why here we use wrapper? Because AbsListView.setMultiChoiceModeListener(MultiChoiceModeListener listener) will wrap our mMultiChoiceModeListener, so we can't not use directly.