FragmentPagerAdapter 滑动过后界面不显示的解决方案

 @Override
    public Fragment getItem(int position) {
        AllNewsFragment result = null;
        Bundle bundle = new Bundle();
        switch (position) {
            case 0:
                if (mAllNewsFragment == null) {
                    mAllNewsFragment = new AllNewsFragment();
                }
                result = mAllNewsFragment;
                break;
            case 1:
                if (mLastNewsFragment == null) {
                    mLastNewsFragment = new AllNewsFragment();
                }
                result = mLastNewsFragment;
                break;
            case 2:
                if (mShoppingGuideFragment == null) {
                    mShoppingGuideFragment = new AllNewsFragment();
                }
                result = mShoppingGuideFragment;
                break;
            case 3:
                if (mNewCarNewsFragment == null) {
                    mNewCarNewsFragment = new AllNewsFragment();
                }
                result = mNewCarNewsFragment;
                break;
            case 4:
                if (mEvaluatingFragment == null) {
                    mEvaluatingFragment = new AllNewsFragment();
                }
                result = mEvaluatingFragment;
                break;
            default:
                break;
        }
        return result;
    }

  @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        //做数据保存处理
    }

  @Override
    public void onViewStateRestored(@Nullable Bundle savedInstanceState) {
        super.onViewStateRestored(savedInstanceState);
        //做恢复数据处理
    }