在ViewPager下销毁的片段会发生什么情况？

Question

I have a ViewPager that has 7 pages, and I am retaining 4 of them while navigating and it gets destroyed after being replaced by another 4 set then GC.

 gPager.get().setOffscreenPageLimit(4);

Inside my custom FragmentStatePagerAdapter

@Override public Parcelable saveState() { return null; }

My problem is I am getting null pointer error even though I manually reinitialize the views in the Fragment after it is being destroyed like 'mDrawerLayout' and mDrawerList . Example:

        View rootView = inflater.inflate(R.layout.drawer_layout_fragment, container, false);
        mDrawerLayout = (DrawerLayout) rootView.get().findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) rootView.get().findViewById(R.id.left_drawer);

If the other fragments are destroyed and some are being displayed on the screen in ViewPager's pages. Are these fragments recreated again or just being retained even it undergoes onDestory ?

If Frag2 is destroyed and Frag1 is not. Does the viewPager(located in the Main Activity) will call again the setAdapter ? Or it will automatically skip the setAdapter and go directly to MyCustomPagerAdapter to populate the fragment destroyed?

@Override

public Fragment getItem(int arg0) {
    SavePref saveState = new SavePref(mContext.get());

    switch(arg0){
        /** Android tab is selected */
        case 0:
            Frag f1 = new Frag1()
            return f1;

        case 1:
            Frag f2 = new Frag2()
            return f2;
    }
}

Answer 1

一旦视图分页器销毁了片段，它将使用位置和数组进行重新创建，同时使用InstantiateItem ..中的逻辑。