在OnScrollListener中实现listFragment

Question

我在OnScrollListener中实现了ListFragment接口，当列表的最后一个元素可见但不能工作时，我想要更改文本。我没有找到类似问题的例子(OnScrollListener I)。我的例子：

public class MyListFragment1 extends ListFragment implements OnScrollListener {
  public View view;

public class MyListAdapter extends ArrayAdapter<String> {
    Context myContext;
    List<String> lista;
    public MyListAdapter(Context context, int textViewResourceId,
            List<String> objects) {
        super(context, textViewResourceId, objects);
        myContext = context;
        lista = objects;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        //return super.getView(position, convertView, parent);

        LayoutInflater inflater = 
                (LayoutInflater)myContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View row=inflater.inflate(R.layout.row, parent, false);
        TextView label=(TextView)row.findViewById(R.id.month);
        label.setText(lista.get(position));
        ImageView icon=(ImageView)row.findViewById(R.id.icon);

        //Customize your icon here
        icon.setImageResource(R.drawable.ic_launcher);

        return row;
    }



}



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

    /*
    ListAdapter myListAdapter = new ArrayAdapter<String>(
            getActivity(),
            android.R.layout.simple_list_item_1,
            month);
    setListAdapter(myListAdapter);
    */
    List<String> lista = new ArrayList<String>();

    lista.add("January");
    lista.add("February");
    lista.add("March");
    lista.add("April");
    lista.add("May");
    lista.add("June");
    lista.add("July");
    lista.add("August");
    lista.add("September");
    lista.add("October");
    lista.add("November");
    lista.add("December");

    MyListAdapter myListAdapter = 
            new MyListAdapter(getActivity(), R.layout.row, lista);
    setListAdapter(myListAdapter);

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    view = inflater.inflate(R.layout.listfragment1, container, false);

    changeText("jestem tutaj");

    return view;
}
private void changeText(String txt){
    TextView nowy = (TextView)view.findViewById(R.id.article);
    nowy.setText(txt);
}

@Override
public void onListItemClick(ListView l, View v, int position, long id) {
    Toast.makeText(
            getActivity(), 
            getListView().getItemAtPosition(position).toString(), 
            Toast.LENGTH_LONG).show();
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
        int visibleItemCount, int totalItemCount) {

    if (++firstVisibleItem + visibleItemCount > totalItemCount) {
        changeText("something");
    }

}

@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
    // TODO Auto-generated method stub

}

我没有任何错误，只是不起作用;)

我在onScroll中发现的P.S方法的实现。

编辑:/添加logcat：

    10-14 01:11:34.944: E/AndroidRuntime(817): FATAL EXCEPTION: main
10-14 01:11:34.944: E/AndroidRuntime(817): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.exercise.AndroidListFragment/com.exercise.AndroidListFragment.AndroidListFragmentActivity}: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.os.Handler.dispatchMessage(Handler.java:99)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.os.Looper.loop(Looper.java:137)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.ActivityThread.main(ActivityThread.java:5041)
10-14 01:11:34.944: E/AndroidRuntime(817):  at java.lang.reflect.Method.invokeNative(Native Method)
10-14 01:11:34.944: E/AndroidRuntime(817):  at java.lang.reflect.Method.invoke(Method.java:511)
10-14 01:11:34.944: E/AndroidRuntime(817):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-14 01:11:34.944: E/AndroidRuntime(817):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-14 01:11:34.944: E/AndroidRuntime(817):  at dalvik.system.NativeStart.main(Native Method)
10-14 01:11:34.944: E/AndroidRuntime(817): Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
10-14 01:11:34.944: E/AndroidRuntime(817):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:270)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.Activity.setContentView(Activity.java:1881)
10-14 01:11:34.944: E/AndroidRuntime(817):  at com.exercise.AndroidListFragment.AndroidListFragmentActivity.onCreate(AndroidListFragmentActivity.java:11)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.Activity.performCreate(Activity.java:5104)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
10-14 01:11:34.944: E/AndroidRuntime(817):  ... 11 more
10-14 01:11:34.944: E/AndroidRuntime(817): Caused by: java.lang.IllegalStateException: Content view not yet created
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.ListFragment.ensureList(ListFragment.java:386)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.ListFragment.getListView(ListFragment.java:280)
10-14 01:11:34.944: E/AndroidRuntime(817):  at com.exercise.AndroidListFragment.MyListFragment1.onCreateView(MyListFragment1.java:93)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.Fragment.performCreateView(Fragment.java:1695)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:861)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1035)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1137)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.app.Activity.onCreateView(Activity.java:4717)
10-14 01:11:34.944: E/AndroidRuntime(817):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:680)
10-14 01:11:34.944: E/AndroidRuntime(817):  ... 21 more

编辑2:我试过findViewById，但它不太管用.

Answer 1

您已经实现了OnScrollListener，但是没有将它附加到您的ListView上。

getListView().setOnScrollListener(this);

将其添加到onCreateView方法中。

Answer 2

您有此错误，因为在尚未创建Listview时，您正在尝试访问Listview。

由: java.lang.IllegalStateException: Content视图尚未创建引起

清单视图实际上是由onCreateView方法的最后一行创建的，它通常如下所示：

return inflater.inflate(R.layout.fragment_list, container, false);

解决方案是从onActivityCreated方法访问列表，该方法在onCreateView方法之后执行。

    @Override
    public void onActivityCreated (Bundle savedInstanceState){
        // Always call the superclass so it can save the view hierarchy state
        super.onCreate(savedInstanceState);

        getListView().setOnScrollListener(this);
    }