android - 为什么执行 listview.setAdapter(_adapter) 两次会使应用程序崩溃？

Question

我遇到的关键问题是 lv_apps.setAdapter(_adapter) TWICE 导致我的应用崩溃。(基本上，当我第二次调用 populateListView_trial() 时，应用程序崩溃了——违规行是 lv_apps.setAdapter(_adapter)

堆栈跟踪在函数下面

private void populateListView_trial() {

    blockedApps = loadArrayBlockedApps();

    if(isTimerRunning()) {
        blockedApps = loadArrayBlockedApps();
        temp_blockedList = new ArrayAdapter<String>(
                MainActivityCircularSeekbar.this,
                android.R.layout.simple_list_item_1, blockedApps);
    } else {

        holder = new ArrayList<Datamodel>();


        for(Map.Entry<String, String> entry : list_installedApps.entrySet()) {

            Datamodel _appdata = new Datamodel();
            _appdata.setAppname(entry.getKey());
            _appdata.setSelected(true);

            try {
                _appdata.setAppIcon(getIconFromPackageName(entry.getValue(), this));
            } catch (Exception e) {
                e.printStackTrace();
            } catch (OutOfMemoryError e) {
                e.printStackTrace();
            }

            holder.add(_appdata);
        }

        _adapter = new MyAdapter(getApplicationContext(), holder);
        try {

            lv_apps.setAdapter(_adapter);

        } catch (Exception e) {
            Log.v(TAG_debug, " caught exception in line 2097, STACKTRACE =");               
        }

    }

}



    @SuppressWarnings("null")
private Map<String, String> getInstalledAppsList() {
    List<String> l_installedApps = new ArrayList<String>();

    //List<Map<String, String>> map_installedApps = new ArrayList<Map<String, String>>();

    Map<String, String> map_installedApps = new HashMap<String, String>();

    List<PackageInfo> allPackagesList = getPackageManager().getInstalledPackages(PackageManager.GET_META_DATA);

    PackageManager pm = getPackageManager();

    for(int i = 0 ; i < allPackagesList.size() ; i++) {
        PackageInfo p = allPackagesList.get(i);
        String appname = p.applicationInfo.loadLabel(pm).toString();
        String packageName = p.packageName;

        map_installedApps.put(appname, packageName);

        //l_installedApps.add(appname);
    }

    return map_installedApps;   
}

违规行:05-26 22:35:44.304: E/AndroidRuntime(4168): java.lang.IllegalStateException: 观察者 android.widget.AbsListView$AdapterDataSetObserver@529347d0 未注册。

我该如何解决这个问题？？？我需要更新 ListView 中的各种元素。

05-26 22:35:40.408: E/OpenGLRenderer(4168): Getting MAX_TEXTURE_SIZE from GradienCache
05-26 22:35:40.412: E/OpenGLRenderer(4168): Getting MAX_TEXTURE_SIZE from Caches::initConstraints()
05-26 22:35:44.304: E/AndroidRuntime(4168): FATAL EXCEPTION: main
05-26 22:35:44.304: E/AndroidRuntime(4168): java.lang.IllegalStateException: Observer android.widget.AbsListView$AdapterDataSetObserver@529347d0 was not registered.
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.database.Observable.unregisterObserver(Observable.java:69)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.widget.BaseAdapter.unregisterDataSetObserver(BaseAdapter.java:42)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.widget.AbsListView.onDetachedFromWindow(AbsListView.java:2638)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.view.View.dispatchDetachedFromWindow(View.java:12160)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:2570)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:2568)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.view.ViewGroup.removeAllViewsInLayout(ViewGroup.java:3960)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.view.ViewGroup.removeAllViews(ViewGroup.java:3904)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.widget.TabHost.clearAllTabs(TabHost.java:251)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at     com.mavdev.focusoutfacebook.MainActivityCircularSeekbar$LoadALLAppsList.onPostExecute(MainActivityCircularSeekbar.java:2480)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at com.mavdev.focusoutfacebook.MainActivityCircularSeekbar$LoadALLAppsList.onPostExecute(MainActivityCircularSeekbar.java:1)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.os.AsyncTask.finish(AsyncTask.java:631)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at  android.os.AsyncTask.access$600(AsyncTask.java:177)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.os.Looper.loop(Looper.java:137)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at android.app.ActivityThread.main(ActivityThread.java:5103)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at java.lang.reflect.Method.invokeNative(Native Method)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at java.lang.reflect.Method.invoke(Method.java:525)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
05-26 22:35:44.304: E/AndroidRuntime(4168):     at dalvik.system.NativeStart.main(Native Method)
05-26 22:36:56.648: E/OpenGLRenderer(4237): Getting MAX_TEXTURE_SIZE from GradienCache
05-26 22:36:56.656: E/OpenGLRenderer(4237): Getting MAX_TEXTURE_SIZE from Caches::initConstraints()
05-26 22:37:00.256: E/AndroidRuntime(4237): FATAL EXCEPTION: main
05-26 22:37:00.256: E/AndroidRuntime(4237): java.lang.IllegalStateException: Observer android.widget.AbsListView$AdapterDataSetObserver@529379f0 was not registered.
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.database.Observable.unregisterObserver(Observable.java:69)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.widget.BaseAdapter.unregisterDataSetObserver(BaseAdapter.java:42)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.widget.AbsListView.onDetachedFromWindow(AbsListView.java:2638)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.view.View.dispatchDetachedFromWindow(View.java:12160)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:2570)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:2568)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.view.ViewGroup.removeAllViewsInLayout(ViewGroup.java:3960)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.view.ViewGroup.removeAllViews(ViewGroup.java:3904)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.widget.TabHost.clearAllTabs(TabHost.java:251)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at com.mavdev.focusoutfacebook.MainActivityCircularSeekbar$LoadALLAppsList.onPostExecute(MainActivityCircularSeekbar.java:2480)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at com.mavdev.focusoutfacebook.MainActivityCircularSeekbar$LoadALLAppsList.onPostExecute(MainActivityCircularSeekbar.java:1)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.os.AsyncTask.finish(AsyncTask.java:631)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.os.AsyncTask.access$600(AsyncTask.java:177)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.os.Looper.loop(Looper.java:137)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at android.app.ActivityThread.main(ActivityThread.java:5103)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at java.lang.reflect.Method.invokeNative(Native Method)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at java.lang.reflect.Method.invoke(Method.java:525)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
05-26 22:37:00.256: E/AndroidRuntime(4237):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

正确填充 ListView 的关键是使用 arrayAdapter:只需更新数组，清除 ListView ，添加新项目，并通知 ListView ，它的数据已更改:

private ArrayAdapter<String> itemsAdapter = 
new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, loadArrayBlockedApps());

初始化 View 时，确保 arrayAdapter 链接到 listView:

ListView listView = (ListView) findViewById(R.id.listView1);
listView.setAdapter(itemsAdapter);

现在在您想要实际调整数组的方法中执行如下操作:

itemsAdapter.clear();
itemsAdapter.addAll(loadArrayBlockedApps());
itemsAdapter.notifyDatasetChanged();