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我想在我的列表视图中显示一个按钮，以防我没有数据可以通过自定义数组适配器填充列表。如果我有数据并且我的列表视图被数据项填充，那么一切正常，但是如果我没有数据项显示列表视图应该显示 ID 为“@android:id/empty”的 LinearLayout，但它从未显示出来，我的应用程序在这个阶段崩溃了。在我的FavoriteStudents.java类文件中，我定义了一个 AsyncTask 。在doInBackground方法中我检查如果我的手机内存中存在最喜欢的文件来为列表视图创建适配器，如果没有，则停止 AsyncTask 并仅使用一个按钮显示列表视图。从 doInBackground 方法返回后，它崩溃并显示此错误：

10-16 16:06:37.568: E/WindowManager(274): Activity com.example.hellogridview.FavoriteStudets has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@44bfea80 that was originally added here
10-16 16:06:37.568: E/WindowManager(274): android.view.WindowLeaked: Activity com.example.hellogridview.FavoriteStudents has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@44bfea80 that was originally added here
10-16 16:06:37.568: E/WindowManager(274):   at android.view.ViewRoot.<init>(ViewRoot.java:227)
10-16 16:06:37.568: E/WindowManager(274):   at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
10-16 16:06:37.568: E/WindowManager(274):   at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
10-16 16:06:37.568: E/WindowManager(274):   at android.view.Window$LocalWindowManager.addView(Window.java:424)
10-16 16:06:37.568: E/WindowManager(274):   at android.app.Dialog.show(Dialog.java:239)
10-16 16:06:37.568: E/WindowManager(274):   at com.example.hellogridview.FavoriteStudents$readingFavFileTask.onPreExecute(FavoriteStudents.java:50)
10-16 16:06:37.568: E/WindowManager(274):   at android.os.AsyncTask.execute(AsyncTask.java:391)
10-16 16:06:37.568: E/WindowManager(274):   at com.example.hellogridview.FavoriteStudents.onCreate(FavoriteStudents.java:34)
10-16 16:06:37.568: E/WindowManager(274):   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-16 16:06:37.568: E/WindowManager(274):   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
10-16 16:06:37.568: E/WindowManager(274):   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
10-16 16:06:37.568: E/WindowManager(274):   at android.app.ActivityThread.access$2200(ActivityThread.java:119)
10-16 16:06:37.568: E/WindowManager(274):   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
10-16 16:06:37.568: E/WindowManager(274):   at android.os.Handler.dispatchMessage(Handler.java:99)
10-16 16:06:37.568: E/WindowManager(274):   at android.os.Looper.loop(Looper.java:123)
10-16 16:06:37.568: E/WindowManager(274):   at android.app.ActivityThread.main(ActivityThread.java:4363)
10-16 16:06:37.568: E/WindowManager(274):   at java.lang.reflect.Method.invokeNative(Native Method)
10-16 16:06:37.568: E/WindowManager(274):   at java.lang.reflect.Method.invoke(Method.java:521)
10-16 16:06:37.568: E/WindowManager(274):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
10-16 16:06:37.568: E/WindowManager(274):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
10-16 16:06:37.568: E/WindowManager(274):   at dalvik.system.NativeStart.main(Native Method)

我的xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@+id/studentsList"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:divider="#b5b5b5"
        android:dividerHeight="1dp"
        android:listSelector="@drawable/student_list_selector" >
    </ListView>

    <!-- empty view -->

    <LinearLayout
        android:id="@android:id/empty"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <Button
            android:id="@+id/addStudents"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Add Students" >
        </Button>
    </LinearLayout>

</LinearLayout>

我的学生适配器

public class StudentsAdapter extends ArrayAdapter<Students> {

    private Context context;
    ImageDownloaderNew imageDownloader;
    ArrayList<Students> students;
    Songs studentsTemp = null;
    int targetWidth = 70;
    int targetHeight = 110;

    public StudentsAdapter (Context context, int textViewResourceId,
            ArrayList<Students> students) {
        super(context, textViewResourceId, songs);
        // TODO Auto-generated constructor stub
        this.context = context;
        this.students= students;
        imageDownloader = new ImageDownloaderNew();
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub

        return students.size();
    }

    @Override
    public Students getItem(int position) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return 0;
    }

    static class ViewHolder {
        protected TextView studentTitle;
        protected RatingBar studentRating;
        protected TextView studentViews;
        protected ImageView studentImage;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub

        //My getView code goes here.I have not pasted here
        return convertView;

    }

}

现在FavoriteStudents.java 类文件

public class FavoriteStudents extends SherlockActivity {

    ListView list;
    StudentsAdapter adapter;
    ArrayList<Students> studentsListArray = new ArrayList<Students>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        setContentView(R.layout.students_list);

        new readingFavFileTask().execute(UtilityFuctions.FAV_STUDENTS_FILE_NAME);
    }

    private class readingFavFileTask extends AsyncTask<String, Void, String> {

        ProgressDialog m_dialog = new ProgressDialog(FavoriteStudents.this);

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            super.onPreExecute();
            // initialize the dialog
            m_dialog.setTitle("Loading...");
            m_dialog.setMessage("Please wait while loading...");
            m_dialog.setIndeterminate(true);
            m_dialog.setCancelable(true);
            m_dialog.show();

        }

        @Override
        protected String doInBackground(String... params) {

            if (!UtilityFuctions.isFileExists(getApplicationContext(),
                    params[0])) {
                // favorite file does not exists
                finish();
                return "fileDoesNotExists";
            }else{
            StudentsListArray = UtilityFuctions.readFavJSONFile(
                    getApplicationContext(), params[0]);
            if (isCancelled())
                finish();
            return null;}
        }

        @Override
        protected void onPostExecute(String result) {
            list = (ListView) findViewById(R.id.studentsList);
            if (result.equals("fileDoesNotExists")) {
                adapter = new StudentsAdapter(FavoriteStudents.this, 1,
                        studentsListArray);
                list.setAdapter(adapter);
                            LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
            View myView = inflater.inflate(R.layout.empty_view, null);
                            list.setEmptyView(myView);
                            m_dialog.dismiss();

            } else {
                // Creating a StudentsAdapter and setting it on listview

                adapter = new StudentsAdapter(FavoriteStudents.this, 1,
                        studentsListArray);
                list.setAdapter(adapter);
                m_dialog.dismiss();

                // Click event for single list row
                list.setOnItemClickListener(new OnItemClickListener() {

                    @Override
                    public void onItemClick(AdapterView<?> parent, View view,
                            int position, long id) {
                                      //onItemClick code goes here

                    }
                });
            }
        }
    }

}

EDIT: @Rolf Smith answer is correct.But The main problem is I am calling finish() in my doInBackground() method which is killing my activity and not showing me the emptyView.So i just remove finish() and everything working perfectly. Thanks EveryOne

4

1 回答 1

6

The empty view (using the android empty id) only works when you use a ListActivity or ListFragment, in this case you have to do the logic your self using the setEmptyView() method.

ListView.setEmptyView()

and the crash you got is probably because the dialog you have shown is not dismissed when your activity closes. So for example in the onPause method call the dismiss method from the dialog you have shown.

Rolf

Edit see comments:

The empty view will be shown with View.GONE and View.VISIBLE this means that you don't need to add it your self etc.

Take a look at this code: And take a good look at the onCreate method.

import android.widget.ListView;

public class FavoriteStudents extends SherlockActivity {

    ListView list;
    StudentsAdapter adapter;
    ArrayList<Students> studentsListArray = new ArrayList<Students>();
    private ListView list;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        setContentView(R.layout.students_list);
        list = (ListView) findViewById(R.id.studentsList);

        View empty = findViewById(R.id.empty_view);
        list.setEmptyView(empty);

        new readingFavFileTask().execute(UtilityFuctions.FAV_STUDENTS_FILE_NAME);
    }

    private class readingFavFileTask extends AsyncTask<String, Void, String> {

        ProgressDialog m_dialog = new ProgressDialog(FavoriteStudents.this);

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            super.onPreExecute();
            // initialize the dialog
            m_dialog.setTitle("Loading...");
            m_dialog.setMessage("Please wait while loading...");
            m_dialog.setIndeterminate(true);
            m_dialog.setCancelable(true);
            m_dialog.show();

        }

        @Override
        protected String doInBackground(String... params) {

            if (!UtilityFuctions.isFileExists(getApplicationContext(),
                    params[0])) {
                // favorite file does not exists
                finish();
                return "fileDoesNotExists";
            }else{
            StudentsListArray = UtilityFuctions.readFavJSONFile(
                    getApplicationContext(), params[0]);
            if (isCancelled())
                finish();
            return null;}
        }

        @Override
        protected void onPostExecute(String result) {
            if (result.equals("fileDoesNotExists")) {
                adapter = new StudentsAdapter(FavoriteStudents.this, 1, studentsListArray);
                list.setAdapter(adapter);
                m_dialog.dismiss();

            } else {
                // Creating a StudentsAdapter and setting it on listview

                adapter = new StudentsAdapter(FavoriteStudents.this, 1,
                        studentsListArray);
                list.setAdapter(adapter);
                m_dialog.dismiss();

                // Click event for single list row
                list.setOnItemClickListener(new OnItemClickListener() {

                    @Override
                    public void onItemClick(AdapterView<?> parent, View view,
                            int position, long id) {
                                      //onItemClick code goes here

                    }
                });
            }
        }
    }

}
于 2012-10-16T10:48:24.287 回答