Question

我创建了一个名为spinner_fn()的函数。但是当调用此函数时，它会显示NullPointerException。所有值都来自数据库。有人可以帮我解决这个问题吗？

源代码

    ... 
    String result = DatabaseUtility.executeQueryPhp("initialName","");
    System.out.print(result);

    try
    {
        JSONArray JA = new JSONArray(result);

        initial_name = new String[JA.length()];
        initial_id = new String[JA.length()];

        String initialname="";
        String initialid="";

        for(int i=0;i<JA.length();i++)
        {
            initialname = JA.getJSONObject(i).getString("initial_name");
            initialid = JA.getJSONObject(i).getString("initial_id");
            initialMap.put(initialname,initialid);
        }

        spinner_fn();
    }
    catch(Exception e)
    {
        Log.e("Fail 3", e.toString());
        e.printStackTrace();
    }
}

private void spinner_fn() {
    ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(
            getApplicationContext(), android.R.layout.simple_spinner_item,
            initial_name);
    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    initial.setAdapter(dataAdapter);

    initial.setOnItemSelectedListener(new OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> arg0, View arg1,
                int position, long id) {

            Log.e("Position new", initial_name[position]);
        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0) {

        }
    });

logcat的

11-03 07:27:36.161: E/AndroidRuntime(2896): FATAL EXCEPTION: main
11-03 07:27:36.161: E/AndroidRuntime(2896): java.lang.NullPointerException
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:193)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.Spinner.onMeasure(Spinner.java:439)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:1034)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:590)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.ScrollView.measureChildWithMargins(ScrollView.java:1217)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.ScrollView.onMeasure(ScrollView.java:321)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.View.measure(View.java:15518)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.Choreographer.doCallbacks(Choreographer.java:562)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.Choreographer.doFrame(Choreographer.java:532)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.os.Handler.handleCallback(Handler.java:725)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.os.Handler.dispatchMessage(Handler.java:92)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.os.Looper.loop(Looper.java:137)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at android.app.ActivityThread.main(ActivityThread.java:5041)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at java.lang.reflect.Method.invokeNative(Native Method)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at java.lang.reflect.Method.invoke(Method.java:511)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
11-03 07:27:36.161: E/AndroidRuntime(2896):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

initial_name = new String[JA.length()];

...

ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(
        getApplicationContext(), android.R.layout.simple_spinner_item,
        initial_name);

您的initial_name数组已满null秒，因为您尚未在其中指定任何值。所有ArrayAdapter数组元素都必须为非null。

猜猜你想改变

for(int i=0;i<JA.length();i++)
    {
        initialname = JA.getJSONObject(i).getString("initial_name");

类似

for(int i=0;i<JA.length();i++)
    {
        initial_name[i] = JA.getJSONObject(i).getString("initial_name");

在ArrayAdapter上获取NullPointerException

1 个答案: