Почему я получаю исключение NullPointerException при использовании setCurrentText или setText для TextSwitcher?

TextSwitcher является частью строки ListView (определенной в xml). Я определяю текст TextSwitcher в setViewValue:

switch(viewId) {
case R.id.tw_text:
    TextSwitcher twText = (TextSwitcher) view;
    twText.setCurrentText("test text");
    return true;

Этот код отлично работает, если twText равно TextView . Но он возвращает NullPointerException с TextSwitcher :

05-22 10:24:08.781: ERROR/AndroidRuntime(3348): FATAL EXCEPTION: main
05-22 10:24:08.781: ERROR/AndroidRuntime(3348): java.lang.NullPointerException
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.TextSwitcher.setCurrentText(TextSwitcher.java:89)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at my.package.MainActivity$1.setViewValue(MainActivity.java:87)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.SimpleCursorAdapter.bindView(SimpleCursorAdapter.java:126)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.CursorAdapter.getView(CursorAdapter.java:186)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.AbsListView.obtainView(AbsListView.java:1315)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.ListView.measureHeightOfChildren(ListView.java:1198)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.ListView.onMeasure(ListView.java:1109)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1012)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:696)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:306)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1012)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:381)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:304)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:526)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:304)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.View.measure(View.java:8171)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewRoot.performTraversals(ViewRoot.java:801)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1727)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.os.Looper.loop(Looper.java:123)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at android.app.ActivityThread.main(ActivityThread.java:4627)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at java.lang.reflect.Method.invokeNative(Native Method)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at java.lang.reflect.Method.invoke(Method.java:521)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-22 10:24:08.781: ERROR/AndroidRuntime(3348):     at dalvik.system.NativeStart.main(Native Method)

Обновление 1 : выглядит как Мне нужно добавить setFactory () в мой код. Но если я сделаю следующее:

  TextSwitcher twText = (TextSwitcher) view;
  twText.setFactory(new ViewSwitcher.ViewFactory() {
      @Override
      public View makeView() {
      TextView t = new TextView(MainActivity.this);
      return t;
      }
      });

Я получаю еще одну ошибку:

05-22 10:54:42.852: ERROR/AndroidRuntime(3907): java.lang.IllegalStateException: Can't add more than 2 views to a ViewSwitcher
05-22 10:54:42.852: ERROR/AndroidRuntime(3907):     at android.widget.ViewSwitcher.addView(ViewSwitcher.java:64)
05-22 10:54:42.852: ERROR/AndroidRuntime(3907):     at android.widget.TextSwitcher.addView(TextSwitcher.java:67)
05-22 10:54:42.852: ERROR/AndroidRuntime(3907):     at android.view.ViewGroup.addView(ViewGroup.java:1845)

Обновление 2 : Я добавил twText.removeAllViews () перед twText.setFactory () . Это работает, но похоже, не лучший способ снова удалить и добавить Просмотры. Как я могу проверить, есть ли представления?

Кроме того, я хотел бы сохранить форматирование / стиль моего TextSwitcher в xml. Использование setFactory не позволяет мне этого сделать. Что я могу сделать?