/**
 * FragmentPagerAdapter和FragmentStatePagerAdapter最大的区别就是instantiateItem和 destroyItem实现不一样,如果都重写了2者的效果就基本一样了
 * 重写instantiateItem ，destroyItem 滑动切换 Fragment数据保存状态
 */

public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
//public class MyFragmentPagerAdapter extends FragmentStatePagerAdapter{
    private List<Pair<String, Fragment>> mFragmentPair;
    private FragmentManager mFragmentManager;

    public MyFragmentPagerAdapter(FragmentManager fm, List<Pair<String, Fragment>> mFragmentPair) {
        super(fm);
        this.mFragmentManager = fm;
        this.mFragmentPair = mFragmentPair;
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentPair.get(position).second;
    }

    @Override
    public int getCount() {
        return mFragmentPair.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentPair.get(position).first;
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        Fragment fragment = (Fragment) super.instantiateItem(container, position);
        mFragmentManager.beginTransaction().show(fragment).commitAllowingStateLoss();
        //###return super.instantiateItem(container, position);
        return fragment;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        //###super.destroyItem(container, position, object);
        Fragment fragment = mFragmentPair.get(position).second;
        mFragmentManager.beginTransaction().hide(fragment).commitAllowingStateLoss();
    }

}