Question

我正在开发类似下一个的片段类：

public class DemandFragment extends Fragment implements LocationListener{...

我已声明：

Spinner spinner_loc;
ArrayAdapter<String> spinner_loc_adapter = null;

@Override
    public void onActivityCreated(Bundle state){

        super.onActivityCreated(state);
        Bundle bundle = this.getArguments();
        source_category = Integer.parseInt(bundle.getString("category"));

        prepareSpinner();
...

我有从onActivityCreated方法调用它的下一个函数（模块化代码）：

private void prepareSpinner(){

        spinner_loc = (Spinner) getView().findViewById(R.id.spinner_loc);
...

进一步......在prepareSpinner（）方法内部。

spinner_loc = null;
spinner_loc_adapter = null;
spinner_loc_adapter = new ArrayAdapter<String>(getActivity(), R.layout.spinner_content, values);
spinner_loc.setAdapter(spinner_loc_adapter);
spinner_loc_adapter.notifyDataSetChanged();

值是一个字符串数组。

问题：我在spinner_loc_adapter上遇到空指针异常。我相信错误是背景，但我无法弄清楚原因。

必须包含的内容：Fragment_class - ＆gt; oncreate（） - ＆gt; prepareSpinner（）??

我在声明中尝试使用Context _c，并将其传递给适配器以代替getActivity（），但我得到了同样的错误。

logcat的

03-24 12:51:46.605  12785-12785/com.test E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.NullPointerException
            at com.test.fragment.DemandFragment.prepareSpinner(DemandFragment.java:330)
            at com.test.fragment.DemandFragment.onActivityCreated(DemandFragment.java:95)
            at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1508)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
            at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
            at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
            at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440)
            at android.os.Handler.handleCallback(Handler.java)
            at android.os.Handler.dispatchMessage(Handler.java)
            at android.os.Looper.loop(Looper.java)
            at android.app.ActivityThread.main(ActivityThread.java)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
            at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
            at dalvik.system.NativeStart.main(Native Method)

XML：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment_content"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:background="@android:color/white">

    <ScrollView
        android:layout_weight="0.9"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:overScrollMode="never"
        android:scrollbars="none">

        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <LinearLayout
                android:id="@+id/layout_select"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical"
                android:background="#1794d4"
                android:alpha="0.9"
                android:layout_marginLeft="30dp"
                android:layout_marginRight="30dp">

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textColor="@android:color/white"
                    android:text="@string/offer_location"
                    android:textSize="18sp"
                    android:layout_marginTop="20dp"
                    android:layout_marginLeft="15dp"
                    android:id="@+id/offer_location" />

                <Spinner
                    android:id="@+id/spinner_location"
                    android:layout_width="fill_parent"
                    android:layout_height="30dp"
                    android:layout_marginLeft="15dp"
                    android:layout_marginRight="15dp"
                    android:layout_marginTop="15dp"
                    android:gravity="center_vertical"
                    android:background="@drawable/spinner_button"
                    android:headerDividersEnabled="false"
                    android:footerDividersEnabled="false"
                    android:divider="@drawable/spinner_button"
                    />

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textColor="@android:color/white"
                    android:text="@string/choose_brand_model"
                    android:textSize="18sp"
                    android:layout_marginTop="20dp"
                    android:layout_marginLeft="15dp"
                    android:textIsSelectable="false" />

                <Spinner
                    android:id="@+id/spiner_marca"
                    android:layout_width="fill_parent"
                    android:layout_height="30dp"
                    android:layout_marginLeft="15dp"
                    android:layout_marginRight="15dp"
                    android:layout_marginTop="15dp"
                    android:gravity="center_vertical"
                    android:background="@drawable/spinner_button"
                    android:headerDividersEnabled="false"
                    android:footerDividersEnabled="false"
                    android:divider="@drawable/spinner_button"
                    />

                <Spinner
                    android:id="@+id/spiner_modelo"
                    android:layout_width="fill_parent"
                    android:layout_height="30dp"
                    android:layout_marginLeft="15dp"
                    android:layout_marginRight="15dp"
                    android:layout_marginTop="10dp"
                    android:gravity="center_vertical"
                    android:background="@drawable/spinner_button"
                    android:headerDividersEnabled="false"
                    android:footerDividersEnabled="false"
                    android:divider="@drawable/spinner_button"
                    />

                <Button
                    android:id="@+id/bt_disable_spinner"
                    android:layout_width="fill_parent"
                    android:layout_height="20dp"
                    android:layout_marginLeft="15dp"
                    android:layout_marginRight="15dp"
                    android:layout_marginTop="15dp"
                    android:layout_marginBottom="15dp"
                    android:gravity="center"
                    android:textColor="@drawable/dark_blue_text_button"
                    android:text="@string/brand_not_sure"
                    android:textSize="10sp"
                    android:background="@drawable/dark_blue_border_button"/>

            </LinearLayout>

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textColor="#cccccc"
                android:text="@string/wanted"
                android:layout_below="@id/layout_select"
                android:layout_marginLeft="30dp"
                android:layout_marginTop="10dp"/>

            <LinearLayout
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:gravity="center_horizontal"
                android:id="@+id/layout_options">

                <ImageButton
                    android:id="@+id/bt_add_text"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginRight="50dp"
                    android:background="@android:color/transparent"
                    android:src="@drawable/ic_add_text"/>

                <ImageButton
                    android:id="@+id/bt_add_photo"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginRight="40dp"
                    android:background="@android:color/transparent"
                    android:src="@drawable/ic_add_photo"/>

                <ImageButton
                    android:id="@+id/bt_add_audio"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:background="@android:color/transparent"
                    android:src="@drawable/ic_add_audio"/>
            </LinearLayout>

            <LinearLayout
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:gravity="center_horizontal"
                android:layout_marginTop="20dp"
                android:layout_marginBottom="20dp"
                android:id="@+id/layout_type">

                <Button
                    android:id="@+id/bt_nuevo"
                    android:layout_width="90dp"
                    android:layout_height="20dp"
                    android:textColor="@drawable/gray_text_button"
                    android:text="@string/demand_new"
                    android:textSize="10sp"
                    android:layout_marginRight="10dp"
                    android:background="@drawable/gray_border_button"/>

                <Button
                    android:id="@+id/bt_km0"
                    android:layout_width="90dp"
                    android:layout_height="20dp"
                    android:textColor="@drawable/gray_text_button"
                    android:text="@string/demand_km0"
                    android:textSize="10sp"
                    android:layout_marginRight="10dp"
                    android:background="@drawable/gray_border_button"/>

                <Button
                    android:id="@+id/bt_2mano"
                    android:layout_width="90dp"
                    android:layout_height="20dp"
                    android:textColor="@drawable/gray_text_button"
                    android:text="@string/demand_used"
                    android:textSize="10sp"
                    android:background="@drawable/gray_border_button"/>
            </LinearLayout>

        </LinearLayout>
    </ScrollView>

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:id="@+id/imageViewSend"
        android:src="@drawable/bt_enviar_solicitud"
        android:layout_gravity="center|bottom"
        android:layout_marginTop="10dp"
        android:background="#1794d4"
        android:paddingLeft="80dp"
        android:paddingRight="80dp"
        android:layout_weight="0.1"
        android:layout_alignParentBottom="true"
        />

</LinearLayout>

Answer 1

在片段的onActivtiyCreated中使用bewlow。 spinner_loc可能为null coz getView()返回null。您需要等到创建活动并将片段附加到活动

spinner_loc = (Spinner) getView().findViewById(R.id.spinner_loc);
spinner_loc_adapter = new ArrayAdapter<String>(getActivity(), R.layout.spinner_content, values);
spinner_loc.setAdapter(spinner_loc_adapter);
spinner_loc_adapter.notifyDataSetChanged();

编辑：

 <Spinner
 android:id="@+id/spinner_location"

更改

 spinner_loc = (Spinner) getView().findViewById(R.id.spinner_loc);

到

 spinner_loc = (Spinner) getView().findViewById(R.id.spinner_location);

Answer 2

尝试使用以下代码

View view =inflater.inflate(R.layout.fragment_view,null);
spinner_loc = (Spinner) view.findViewById(R.id.spinner_loc);
spinner_loc_adapter = new ArrayAdapter<String>(getActivity(), R.layout.spinner_content, values);
spinner_loc.setAdapter(spinner_loc_adapter);
spinner_loc_adapter.notifyDataSetChanged();

旋转器和Context的问题？

2 个答案: