java – 如何在ViewPager中加载片段才能选择

im在Viewpager内部使用3个片段,其在大型数据加载器中加载大数据的问题在像HTC这样的设备中运行良好,但是在低端设备需要很多时间.这是因为主要是当我实现pagerAdapter时,我把Fragments放在一个arrayList里面,这样就迫使片段在主体活动时加载.我需要它只是“加载”第一个片段(主)和用户“swype”加载其他片段.它有什么办法来实现吗？这是我的pageAdapater

public class PagerAdapter extends FragmentPagerAdapter  {

    private final ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
   // private final ArrayList<String> titulos = new ArrayList<String>();

   // private int NUM_PAGES =0;
    public PagerAdapter(FragmentManager manager,int num_pages) {
        super(manager);
     //   this.NUM_PAGES = num_pages;
    }


    public void addFragment(Fragment fragment,String title) {
        mFragments.add(fragment);
            notifyDataSetChanged();
    }

    @Override
    public int getCount() {
        //return NUM_PAGES;
       return mFragments.size();
    }

    @Override
    public Fragment getItem(int position) {
        return mFragments.get(position);

    }

}

private boolean _hasLoadedOnce= false; // your boolean field

@Override
public void setUserVisibleHint(boolean isFragmentVisible_) {
    super.setUserVisibleHint(true);


    if (this.isVisible()) {
        // we check that the fragment is becoming visible
        if (isFragmentVisible_ && !_hasLoadedOnce) {
            new NetCheck().execute();
            _hasLoadedOnce = true;
        }
    }
}