@Override
    public Parcelable saveState() {
        Bundle state = null;
        if (mSavedState.size() > 0) {
            state = new Bundle();
            state.putSparseParcelableArray("states", mSavedState.clone());
        }
        int size = mFragments.size();
        for (int i = 0; i < size; i++) {
            int index = mFragments.keyAt(i);
            Fragment f = mFragments.valueAt(i);
            if (f != null && f.isAdded()) {
                if (state == null) {
                    state = new Bundle();
                }
                String key = "f" + index;
                mFragmentManager.putFragment(state, key, f);
            }
        }
        return state;
    }
Return the Fragment associated with a specified position.
library/src/main/java/com/shizhefei/view/indicator/FragmentListPageAdapter.java