Question

当我尝试在按下片段中的按钮时从AutoCompleteTextView中提取文本时，抛出NullPointerException。这是我的代码......

public class TreeMenuFragment extends SherlockFragment{
protected View view; 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
    view = inflater.inflate(R.layout.treemenu, container, false);
    //Auto-Complete
    AutoCompleteTextView autoView = (AutoCompleteTextView) view.findViewById(R.id.edit_message);
    String[] itemOptions = getResources().getStringArray(R.array.edit_message);

    ArrayAdapter<String> theAdapter = 
            new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, itemOptions);
    autoView.setAdapter(theAdapter);
    ((BaseAdapter) autoView.getAdapter()).notifyDataSetChanged();
    ((ViewGroup) autoView.getParent()).removeView(autoView);

    container.addView(autoView);

    Button b = (Button) view.findViewById(R.id.post_blacklist_button);
    b.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            AutoCompleteTextView editText=(AutoCompleteTextView) view.findViewById(R.id.edit_message);
            String blackListItem = editText.getText().toString();

            editText.setText("");
            MainActivity.getInstance().postBlackListItem(blackListItem);

        }
    });
    return view;
}

}

相关的xml在这里：

    <AutoCompleteTextView
    android:id="@+id/edit_message"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="@string/my_hint" />

<Button
    android:id="@+id/post_blacklist_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:hint="@string/update_button" />

* 更新： *当我尝试将自动完成文档转换从v更改为View时，我的日志会打印以下内容：

FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.privacyapp.TreeMenuFragment$1.onClick(TreeMenuFragment.java:34)
at android.view.View.performClick(View.java:2532)
at android.view.View$PerformClick.run(View.java:9293)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:150)
at android.app.ActivityThread.main(ActivityThread.java:4263)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
at dalvik.system.NativeStart.main(Native Method)

Answer 1

更改

AutoCompleteTextView editText=(AutoCompleteTextView) v.findViewById(R.id.edit_message);

到

AutoCompleteTextView editText=(AutoCompleteTextView) view.findViewById(R.id.edit_message);

此处v是您点击的Button，我假设view是膨胀的xml，您可以在其中找到AutoCompleteTextView。这意味着，当您尝试在其上调用函数时，editText为null并抛出NPE

     editText.getText().toString();

如果这不能解决问题，那么请发布logcat，但仍然需要更改此行

将autoView声明为成员变量，然后您只需初始化一次。然后在AutoCompleteTextView内使用onClick的该实例获取文字

Button的OnClickListener中的AutoCompleteTextView NullPointer

1 个答案: