Question

我试图搜索我的问题，但没有成功。我从数据库（Parse.com）填充ArrayAdapter<String> parkingLotAdapter。我将此适配器分配给微调器。 Spinner工作正常，显示项目列表。但是当我尝试通过getPosition(item)获取适配器中的一个项目时，我得到NullPointerException。

List<String> list = new ArrayList<String>();

for (ParseObject temp : parkingList) {
     list.add(temp.getString("parking_lot"));
     }
parkingLotAdapter = new ArrayAdapter<String>(getActivity(),
android.R.layout.simple_spinner_item, list);
parkingLotAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
parkinglotSpinner.setAdapter(parkingLotAdapter);

int pos4 = parkingLotAdapter.getPosition("A123");
parkinglotSpinner.setSelection(pos4);

当我将getPosition(item)与其他我从参考资料中填充并使用ArrayAdapter<CharSequence>的微调器一起使用时，一切正常。你能帮我解决这个问题。

我的Logcat：

06-17 09:40:13.927: W/dalvikvm(26031): threadid=1: thread exiting with uncaught exception (group=0x41307300)
06-17 09:40:13.927: E/AndroidRuntime(26031): FATAL EXCEPTION: main
06-17 09:40:13.927: E/AndroidRuntime(26031): java.lang.NullPointerException
06-17 09:40:13.927: E/AndroidRuntime(26031):    at me.aizon.app.fragments.RegisterFragment$LoadParkingSpinnerASYNC.onPostExecute(RegisterFragment.java:396)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at me.aizon.app.fragments.RegisterFragment$LoadParkingSpinnerASYNC.onPostExecute(RegisterFragment.java:1)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at android.os.AsyncTask.finish(AsyncTask.java:631)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at android.os.AsyncTask.access$600(AsyncTask.java:177)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at android.os.Looper.loop(Looper.java:137)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at android.app.ActivityThread.main(ActivityThread.java:4746)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at java.lang.reflect.Method.invokeNative(Native Method)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at java.lang.reflect.Method.invoke(Method.java:511)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:917)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)
06-17 09:40:13.927: E/AndroidRuntime(26031):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

Try this way,hope this will help you to solve your problem.

You have already list object to try to get index from list instead of adapter.

List<String> list = new ArrayList<String>();

Replace this code:
int pos4 = parkingLotAdapter.getPosition("A123");
parkinglotSpinner.setSelection(pos4);

With this:
parkinglotSpinner.setSelection(list.indexOf("A123"))

ArrayAdapter <string>中的getPosition（item）给出NullPointerException </string>

1 个答案: