Service 为什么要获取nullpointerexception listener.onstart（未知源）？

我在活动上有一个文本到语音的按钮。所说的字符串通过intent传递给侦听器服务类。我最近刚刚在服务的onStart方法中添加了super.onStart，但是Eclipse告诉我这是不推荐的，所以我想知道这是否是我需要做的更改。代码如下：

public class Listener extends Service implements TextToSpeech.OnInitListener {

private String str;
private TextToSpeech mTts;
private static final String TAG = "TTSService";
private ArrayList<Button> b;

@Override
public IBinder onBind(Intent arg0) {

    return null;
}

@Override
public void onCreate() {

    mTts = new TextToSpeech(this, this // OnInitListener
    );
    mTts.setSpeechRate(0.5f);

    super.onCreate();
}

@Override
public void onDestroy() {
    // TODO Auto-generated method stub
    if (mTts != null) {
        mTts.stop();
        mTts.shutdown();
        Log.v(TAG, "ondestroy_service");
    }

    super.onDestroy();
}

@Override
public void onStart(Intent intent, int startId) {

    str = intent.getStringExtra("convo");
    sayHello(str);

    super.onStart(intent, startId);
}

@Override
public void onInit(int status) {
    Log.v(TAG, "oninit");

    mTts.setOnUtteranceProgressListener(new UtteranceProgressListener() {
        @Override
        public void onStart(String utteranceID) {
            for (int i = 0; i < ChooseWord.buttonArrayNoClick.size(); i++) {

                ChooseWord.buttonArrayNoClick.get(i).setClickable(false);
            }

        }

        @Override
        public void onError(String utteranceID) {

        }

        @Override
        public void onDone(String utteranceID) {
            for (int i = 0; i < ChooseWord.buttonArrayNoClick.size(); i++) {
                ChooseWord.buttonArrayNoClick.get(i).setClickable(true);
            }

        }
    });
    if (status == TextToSpeech.SUCCESS) {
        int result = mTts.setLanguage(Locale.US);
        if (result == TextToSpeech.LANG_MISSING_DATA
                || result == TextToSpeech.LANG_NOT_SUPPORTED) {
            Log.v(TAG, "Language is not available.");
        } else {

            sayHello(str);

        }
    } else {
        Log.v(TAG, "Could not initialize TextToSpeech.");
    }
}

private void sayHello(String str) {
    mTts.speak(str, TextToSpeech.QUEUE_FLUSH, null);
}

---

尝试覆盖

onStart命令

而不是

onStart

，并添加一些登录来检查intent和conva！=谢谢你，布兰德尔……我来试试。

java.lang.RuntimeException: Unable to start service com.mresapp.Listener@42060920 with null:        
java.lang.NullPointerException
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2782)
at android.app.ActivityThread.access$2000(ActivityThread.java:152)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1385)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5328)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.homeworkhelper.Listener.onStart(Unknown Source)
at android.app.Service.onStartCommand(Service.java:450)
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2765)