Android cwac无休止的片段演示问题-在我自己的片段格式中使用

我有一个使用ADT向导生成的基本工作应用程序。因此，我使用了一种基本的片段格式（1）

我想以演示代码（2）为例，如果我以片段为例，应用程序崩溃，而logcat将片段显示为故障，则无论如何都要使用它

我试图从（1）和（2）中获取代码，以创建（3）多个错误的发生方式。看了这么多之后，我认为问题出在“DemoAdapter=null”上；因为无论出于什么原因，“类DemoAdapter扩展EndlesAdapter实现IItemsReadyListener”都无法调用

T

（1） 我的基本片段-哪个有效

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class Fragment2 extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_dod_events, container, false);



// Do Stuff Here
        return root;
    }

    @Override public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        // Save some state!
      }
}

（2） 无休止的演示-如果我按原样使用，没有错误，但会使我的应用程序崩溃

package com.commonsware.cwac.endless.demo;

import android.app.ListFragment;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.widget.ArrayAdapter;
import java.util.ArrayList;
import com.commonsware.cwac.endless.EndlessAdapter;

/**
 * This example makes use of EndlessAdapter's
 * setRunInBackground feature.
 * 
 * Calling setRunInBackground(false) allows you to launch
 * your own AsyncTask with a listener callback, rather than
 * using the built in cacheInBackground functionality.
 * 
 * This is useful if you have existing AsyncTask(s) written
 * to fetch data in a background thread, and don't want
 * EndlessAdapter launching that in yet another background
 * thread.
 */
public class EndlessAdapterCustomTaskFragment extends ListFragment {

  DemoAdapter adapter=null;
  ArrayList<Integer> items=null;

  @Override
  public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    setRetainInstance(true);

    if (adapter == null) {
      items=new ArrayList<Integer>();

      for (int i=0; i < 25; i++) {
        items.add(i);
      }

      adapter=new DemoAdapter(items);
      adapter.setRunInBackground(false); // Tell the adapter
                                         // we will handle
                                         // starting the
                                         // background task
    }

    setListAdapter(adapter); 
  }

  class DemoAdapter extends EndlessAdapter implements
      IItemsReadyListener {
    private RotateAnimation rotate=null;

    DemoAdapter(ArrayList<Integer> list) {
      super(new ArrayAdapter<Integer>(getActivity(), R.layout.row,
                                      android.R.id.text1, list));

      rotate=
          new RotateAnimation(0f, 360f, Animation.RELATIVE_TO_SELF,
                              0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
      rotate.setDuration(600);
      rotate.setRepeatMode(Animation.RESTART);
      rotate.setRepeatCount(Animation.INFINITE);
    }

    @Override
    protected View getPendingView(ViewGroup parent) {
      View row=
          getActivity().getLayoutInflater().inflate(R.layout.row, null);

      View child=row.findViewById(android.R.id.text1);

      child.setVisibility(View.GONE);

      child=row.findViewById(R.id.throbber);
      child.setVisibility(View.VISIBLE);
      child.startAnimation(rotate);

      return(row);
    }

    @Override
    protected boolean cacheInBackground() throws Exception {
      new FetchDataTask(this, items.size()).execute();

      return(items.size()<75);
    }

    @Override
    public void onItemsReady(ArrayList<Integer> data) {
      items.addAll(data);
      adapter.onDataReady(); // Tell the EndlessAdapter to
                             // remove it's pending
                             // view and call
                             // notifyDataSetChanged()
    }

    @Override
    protected void appendCachedData() {
    }
  }

  interface IItemsReadyListener {
    public void onItemsReady(ArrayList<Integer> data);
  }

  class FetchDataTask extends AsyncTask<Void, Void, ArrayList<Integer>> {
    IItemsReadyListener listener;

    /*
     * The point from where to start counting. In a real
     * life scenario this could be a pagination number
     */
    int startPoint;

    protected FetchDataTask(IItemsReadyListener listener, int startPoint) {
      this.listener=listener;
      this.startPoint=startPoint;
    }

    @Override
    protected ArrayList<Integer> doInBackground(Void... params) {
      ArrayList<Integer> result=new ArrayList<Integer>();

      SystemClock.sleep(3000); // pretend to do work
      for (int i=startPoint; i < startPoint + 25; i++) {
        result.add(i);
      }

      return(result);
    }

    @Override
    protected void onPostExecute(ArrayList<Integer> result) {
      listener.onItemsReady(result);
    }
  }
}

package com.commonware.cwac.uncentral.demo；
导入android.app.ListFragment；
导入android.os.AsyncTask；
导入android.os.Bundle；
导入android.os.SystemClock；
导入android.view.view；
导入android.view.ViewGroup；
导入android.view.animation.animation；
导入android.view.animation.RotateAnimation；
导入android.widget.ArrayAdapter；
导入java.util.ArrayList；
导入com.commonware.cwac.uncil.EndlessAdapter；
/**
*此示例使用EndlessAdapter的
*设置运行背景功能。
* 
*调用setRunInBackground（false）可以启动
*您自己的异步任务具有侦听器回调，而不是
*使用内置的cacheInBackground功能。
* 
*如果您已经编写了现有的异步任务，这将非常有用
*在后台线程中获取数据，但不希望
*EndlessAdapter在另一个背景下发布
*线。
*/
公共类EndlesAdapterCustomTaskFragment扩展了ListFragment{
DemoAdapter=null；
arraylistitems=null；
@凌驾
已创建ActivityState上的公共无效（Bundle savedInstanceState）{
super.onActivityCreated（savedInstanceState）；
setRetainInstance（真）；
if（适配器==null）{
items=newarraylist（）；
对于（int i=0；i<25；i++）{
项目.添加（i）；
}
适配器=新的DemoAdapter（项目）；
setRunInBackground（false）；//告诉适配器
//我们会处理
//开始
//后台任务
}
setListAdapter（适配器）；
}
类DemoAdapter扩展EndlesAdapter实现
Iitemsradylistener{
私有RotateAimation rotate=null；
DemoAdapter（ArrayList列表）{
超级（新阵列适配器（getActivity（），R.layout.row，
android.R.id.text1，list））；
轮换=
新的旋转动画（0f，360f，动画。相对于自身，
0.5f，动画。相对于自身，0.5f）；
轮换。设定持续时间（600）；
rotate.setRepeatMode（动画.重新启动）；
rotate.setRepeatCount（Animation.INFINITE）；
}
@凌驾
受保护的视图getPendingView（视图组父视图）{
查看行=
getActivity（）.GetLayoutFlater（）充气（R.layout.row，null）；
View child=row.findviewbyd（android.R.id.text1）；
setVisibility（View.GONE）；
child=row.findViewById（R.id.throbber）；
setVisibility（View.VISIBLE）；
child.startAnimation（旋转）；
返回（行）；
}
@凌驾
受保护的布尔cacheInBackground（）引发异常{
新建FetchDataTask（this，items.size（））.execute（）；
返回（items.size（）
import java.util.ArrayList;

import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.support.v4.app.Fragment;
import android.support.v4.app.ListFragment;
import android.support.v4.app.DialogFragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.widget.ArrayAdapter;

import com.commonsware.cwac.endless.EndlessAdapter;

public class Fragment2 extends ListFragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_dod_events, container, false);

        DemoAdapter adapter=null;
        ArrayList<Integer> items=null;  

        @Override
        public void onActivityCreated(Bundle savedInstanceState) {
          super.onActivityCreated(savedInstanceState);

          setRetainInstance(true);

          if (adapter == null) {
            items=new ArrayList<Integer>();

            for (int i=0; i < 25; i++) {
              items.add(i);
            }

            adapter=new DemoAdapter(items);
            adapter.setRunInBackground(false); // Tell the adapter
                                               // we will handle
                                               // starting the
                                               // background task
          }

          setListAdapter(adapter); 
        }

        class DemoAdapter extends EndlessAdapter implements
            IItemsReadyListener {
          private RotateAnimation rotate=null;

          DemoAdapter(ArrayList<Integer> list) {
            super(new ArrayAdapter<Integer>(getActivity(), R.layout.row,
                                            android.R.id.text1, list));

            rotate=
                new RotateAnimation(0f, 360f, Animation.RELATIVE_TO_SELF,
                                    0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
            rotate.setDuration(600);
            rotate.setRepeatMode(Animation.RESTART);
            rotate.setRepeatCount(Animation.INFINITE);
          }

          @Override
          protected View getPendingView(ViewGroup parent) {
            View row=
                getActivity().getLayoutInflater().inflate(R.layout.row, null);

            View child=row.findViewById(android.R.id.text1);

            child.setVisibility(View.GONE);

            child=row.findViewById(R.id.throbber);
            child.setVisibility(View.VISIBLE);
            child.startAnimation(rotate);

            return(row);
          }

          @Override
          protected boolean cacheInBackground() throws Exception {
            new FetchDataTask(this, items.size()).execute();

            return(items.size()<75);
          }

          @Override
          public void onItemsReady(ArrayList<Integer> data) {
            items.addAll(data);
            adapter.onDataReady(); // Tell the EndlessAdapter to
                                   // remove it's pending
                                   // view and call
                                   // notifyDataSetChanged()
          }

          @Override
          protected void appendCachedData() {
          }
        }

        interface IItemsReadyListener {
          public void onItemsReady(ArrayList<Integer> data);
        }

        class FetchDataTask extends AsyncTask<Void, Void, ArrayList<Integer>> {
          IItemsReadyListener listener;

          /*
           * The point from where to start counting. In a real
           * life scenario this could be a pagination number
           */
          int startPoint;

          protected FetchDataTask(IItemsReadyListener listener, int startPoint) {
            this.listener=listener;
            this.startPoint=startPoint;
          }

          @Override
          protected ArrayList<Integer> doInBackground(Void... params) {
            ArrayList<Integer> result=new ArrayList<Integer>();

            SystemClock.sleep(3000); // pretend to do work
            for (int i=startPoint; i < startPoint + 25; i++) {
              result.add(i);
            }

            return(result);
          }

          @Override
          protected void onPostExecute(ArrayList<Integer> result) {
            listener.onItemsReady(result);
          }
        }

// Do Stuff Here
        return root;
    }

    @Override public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        // Save some state!
      }