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

【问题标题】：Why doing listview.setAdapter(_adapter) twice crashes app?为什么执行 listview.setAdapter(_adapter) 两次会使应用程序崩溃？
【发布时间】：2014-05-27 03:43:15
【问题描述】：

我遇到的关键问题是 lv_apps.setAdapter(_adapter) TWICE 是我的应用程序崩溃的原因。（基本上，当我第二次调用 populateListView_trial() 时，应用程序崩溃 - 违规行是 lv_apps.setAdapter(_adapter)

Stacktrace 位于函数下方

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: Observer android.widget.AbsListView$AdapterDataSetObserver@529347d0 未注册。

我怎样才能解决这个问题？？？我需要更新列表视图中的各种元素。

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)

【问题讨论】：

请看这个链接stackoverflow.com/questions/14424030/…grokkingandroid.com/use-contentobserver-to-listen-to-changes
你为什么要调用 popullate listview 两次？
@Rod_Algonquin - 单击按钮时调用此函数。所以如果用户点击按钮两次，它会被调用两次。我每次都需要运行代码，因为我计划根据应用程序中的一些设置更改仅在列表中显示某些应用程序。
堆栈跟踪似乎与您的代码无关。代码中没有AsyncTask。请发布确切的代码。或正确的堆栈跟踪。
不要调用两次setAdapter()，更新适配器中的数据并调用notifyDataSetChanged()

标签： android listview android-listview android-arrayadapter baseadapter

【解决方案1】：

正确填充列表视图的关键是使用 arrayAdapter：只需更新数组，清除列表视图，添加新项目，并通知列表视图，它的数据已更改：

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

初始化视图时，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以下操作：

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

【讨论】：