Question

在我的应用中我有一个片段，我有任何复选框。当我开始使用TextToSpech时。我创建了一个没有片段的类似版本，它工作正常。但是，当我在片段中实现它时，它不起作用。她是我的代码：

public class OneFragment extends Fragment implements TextToSpeech.OnInitListener, CompoundButton.OnCheckedChangeListener {
private TextToSpeech tts;

ListView listView;
ArrayAdapter<Model> adapter;
List<Model> list = new ArrayList<Model>();

public OneFragment() {
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View returnView = inflater.inflate(R.layout.fragment_one, container, false);
    listView = (ListView) returnView.findViewById(R.id.listView);
    adapter = new MyAdapter(getActivity(), getModel());
    listView.setAdapter(adapter);
    final CheckBox chk = (CheckBox)returnView.findViewById(R.id.checkBox);
    chk.setOnCheckedChangeListener(OneFragment.this);

    return returnView;
}

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
        tts = new TextToSpeech(getActivity(), this);
    }
}

private List<Model> getModel() {
    list.add(new Model("Linux", "S"));
    list.add(new Model("Linux", "S"));
    list.add(new Model("Linux", "S"));
    list.add(new Model("Linux", "S"));
    list.add(new Model("Linux", "S"));

    return list;
}

@Override
public void onInit(int status) {
    if (status == TextToSpeech.SUCCESS) {

        int result = tts.setLanguage(Locale.ITALIAN);

        if (result == TextToSpeech.LANG_MISSING_DATA
                || result == TextToSpeech.LANG_NOT_SUPPORTED) {
            Log.e("TTS", "This Language is not supported");
        } else {

            startSpeak();
        }

    } else {
        Log.e("TTS", "Initilization Failed!");
    }
}

private void startSpeak() {
    tts.speak("Ciao", TextToSpeech.QUEUE_FLUSH, null);
}

@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
    CheckBox chk = (CheckBox)getActivity().findViewById(R.id.checkBox);
      for (Model i: list ) {
        if (chk.isChecked()) {
            this.startSpeak();
        }
    }
}
}

这是部分LogCat结果：

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.CheckBox.setOnCheckedChangeListener(android.widget.CompoundButton$OnCheckedChangeListener)' on a null object reference

我该怎么办？

Answer 1

我有一个片段，我有任何复选框

如果CheckBox位于Fragment的{{1}}布局内，则使用R.layout.fragment_one从布局而不是OneFragment.this.getView()访问CheckBox：

getActivity()

或者将CheckBox chk = (CheckBox)OneFragment.this.getView().findViewById(R.id.checkBox);声明为类级变量并在onCreateView中初始化它：

CheckBox chk

带有CheckBox的Fragment中的NullPointException

1 个答案: