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尝试更新 FragmentPagerAdapter 的数据源时出现错误，我尝试在此处搜索，但没有找到类似的东西

我的活动中的代码

@Override
protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);

    private List<Noticia> listaNoticias = new ArrayList<Noticia>();

// Set the adapters
    mPager = (ViewPager) findViewById(R.id.pager);        
    mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
    mPager.setAdapter(mPagerAdapter);

// Get first page from JSON and show in the pager
    listaNoticias = Noticia.getPageFromJSON(1);
    ((ScreenSlidePagerAdapter) mPagerAdapter).setNoticias(listaNoticias);
    mPagerAdapter.notifyDataSetChanged();
}

来自 PageAdapter 的代码

class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter 
 {
        private List<Noticia> noticias = new ArrayList<Noticia>();

        public ScreenSlidePagerAdapter(FragmentManager fm) 
        {
            super(fm);
        }

        public void setNoticias(List<Noticia> listaN)
        {
            noticias = new ArrayList<Noticia>(listaN);
        }

        @Override
        public Fragment getItem(int position) 
        {
            if(position==10)
            {
// Get the second page
                    noticias = Entry.addPageFromJSON(noticias, 2); // I manually checked the ArrayList and its content is OK
                    notifyDataSetChanged();
            }
            EntrySlidePageFragment fragmento = new EntrySlidePageFragment();
            fragmento.setFragment(noticias.get(position));

            return fragmento;   
        }

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

        public int getItemPosition(Object item) 
        {
            return POSITION_NONE;
        }    
 }

当我将新内容添加到 ArrayList 时，应用程序停止工作，并且出现以下错误：

threadid=1: thread exiting with uncaught exception (group=0x40015560)
FATAL EXCEPTION: main
java.lang.NullPointerException
at android.support.v4.app.FragmentStatePagerAdapter.instantiateItem(FragmentStatePagerAdapter.java:119)
at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:829)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1044)
at android.support.v4.view.ViewPager.populate(ViewPager.java:911)
at android.support.v4.view.ViewPager$3.run(ViewPager.java:242)
at android.support.v4.view.ViewPager.completeScroll(ViewPager.java:1757)
at android.support.v4.view.ViewPager.onInterceptTouchEvent(ViewPager.java:1890)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:848)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691)
at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125)
at android.app.Activity.dispatchTouchEvent(Activity.java:2096)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675)
at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2194)
at android.view.ViewRoot.handleMessage(ViewRoot.java:1878)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3683)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
at dalvik.system.NativeStart.main(Native Method)

有人知道这里发生了什么吗？

4

1 回答 1

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我使用 07/2012 打包的较旧版本的android-support-V4自己解决了这个问题，并省略了notifyDataSetChanged()。还不知道是什么原因导致的错误，可能是新版本有一些错误......

于 2013-06-20T08:03:51.693 回答