Android 滚动时隐藏图像

对于片段，我创建了一个自定义类来访问，但现在我想隐藏图像，而不是使用eclipse隐藏工具栏

public Fragment getItem(int position) {
    switch (position) {
    case 0:
        fragmentManager = getActivity().getSupportFragmentManager();
    case 1:
        fragmentManager = getActivity().getSupportFragmentManager();
    case 2:
        fragmentManager = getActivity().getSupportFragmentManager();
        break;
    }

    SamplFragment defaultFragment = SamplFragment.newInstance(position, offerListData);
    return defaultFragment;
}