saving state on compound view widgets

I stumbled across the same issue when trying to create my own compound view. From looking at the Android source code I believe the correct way to implement compound views is for the compound view itself to take on the responsibility of saving and restoring the instance state of its children and to prevent the calls to save and restore instance state from being passed onto the child views. This works around the issue of the IDs of child views not being unique when you have more then one instance of the same compound view in an activity.

This might sound complicated but it is really quite easy and the APIs actually make provision for this exact scenario. I've written a blog post here on how this is done but essentially in your compound view you need to implement the following 4 methods, customising onSaveInstanceState() and onRestoreInstanceState() to meet your specific requirements.

@Override
protected Parcelable onSaveInstanceState() {
    Parcelable superState = super.onSaveInstanceState();
    return new SavedState(superState, numberPicker1.getValue(), numberPicker2.getValue(), numberPicker3.getValue());
}

@Override
protected void onRestoreInstanceState(Parcelable state) {
    SavedState savedState = (SavedState) state;
    super.onRestoreInstanceState(savedState.getSuperState());

    numberPicker1.setValue(savedState.getNumber1());
    numberPicker2.setValue(savedState.getNumber2());
    numberPicker3.setValue(savedState.getNumber3());
}

@Override
protected void dispatchSaveInstanceState(SparseArray container) {
    // As we save our own instance state, ensure our children don't save 
    // and restore their state as well.
    super.dispatchFreezeSelfOnly(container);
}

@Override
protected void dispatchRestoreInstanceState(SparseArray container) {
    /** See comment in {@link #dispatchSaveInstanceState(android.util.SparseArray)} */
    super.dispatchThawSelfOnly(container);
}

Regarding the problem with NumberPicker/TimePicker, as mentioned in another comment there appears to be a bug with NumberPicker and TimePicker. To fix it you could override both and implement the solution I've described.