android viewpage 除了前後fragmet 外，有時可能會將以外的fragment 回收

solution
自訂 FragmentPagerAdapter

HashMap, 

Fragment> cachedFragmentHashMap;

@Overridepublic Fragment getItem(int position) {
    Fragment f = cachedFragmentHashMap.get(position);    if (f != null) {
        return f;    }else{
            f = OtherFragment.newInstance();            break;    }
    cachedFragmentHashMap.put(position, f);    return f;}
 @Override    public void destroyItem(ViewGroup container, int position, Object object) {
//        super.destroyItem(container, position, object);       
    }