fragment里嵌套fragmentstatepageradapter出问题 好几天了求帮忙

新手遇到一些问题 好像是包的引用方面的错误？ 我也不太明白 求教啊


import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class Fragmentforum extends Fragment {
private ArrayList<Fragment> fragmentlist;
private ViewPager viewpager;
private FragmentStatePagerAdapter mAdapter;

@Override
public void onAttach(Activity activity) {
// TODO Auto-generated method stub
super.onAttach(activity);

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view=inflater.inflate(R.layout.layout_forum,container,false);
viewpager=(ViewPager)view.findViewById(R.id.viewpager);
fragmentlist=new ArrayList<Fragment>();
fragmentlist.add(new Fragment1());
fragmentlist.add(new Fragment2());
fragmentlist.add(new Fragment3());
fragmentlist.add(new Fragment4());
viewpager.setAdapter(new MyFragmentPagerAdapter(getActivity().getFragmentManager(),fragmentlist));
return view;
}

public List<String> getData() {
List<String> list = new ArrayList<String>();
for (int i = 0; i < 30; i++) {
list.add("文章" + i);// 模拟文章的标题
}
return list;
}



public class MyFragmentPagerAdapter extends FragmentStatePagerAdapter {

public MyFragmentPagerAdapter(android.support.v4.app.FragmentManager fm) {
super(fm);
// TODO Auto-generated constructor stub
}

@Override
public Fragment getItem(int arg0) {
// TODO Auto-generated method stub
return fragmentlist.get(arg0);
}

@Override
public int getCount() {
// TODO Auto-generated method stub
return fragmentlist.size();
}

}


}

在getitem() 函数里出问题 The return type is incompatible with FragmentStatePagerAdapter.getItem(int)

求教求教 另外现在版本高了 是不是能不引用V4包就不引用V4啊