Question

我需要在背景服务中启动倒计时器并在My片段上显示它。这就是我目前所处的位置。

调用startService后，ComponentName c为null。我不知道如何使用调试器来调试它。

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


        View rootView = inflater.inflate(R.layout.home_map, container, false);

        setUpMapIfNeeded();
        controlv = rootView.findViewById(R.id.controls_parked);
        parker_info = (TextView)rootView.findViewById(R.id.parked_info);
        take_to_car_btn= (Button)rootView.findViewById(R.id.walk_to_Car);
        unPark = (Button)rootView.findViewById(R.id.un_park);
        timer = (Button)rootView.findViewById(R.id.timer_btn);
        myContext = getActivity();
        mDpi = getActivity().getResources().getDisplayMetrics().densityDpi;


        timer.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                ComponentName c = getActivity().startService(new Intent(getActivity(), TimerService.class));
                Log.i(TAG, "Started service");


            }
        });

        return rootView;

    }

private BroadcastReceiver br = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            updateGUI(intent); // or whatever method used to update your GUI fields
        }
    };

    private void updateGUI(Intent intent){
        if (intent.getExtras() != null) {
            long millisUntilFinished = intent.getLongExtra("countdown", 0);
            Log.i(TAG, "Countdown seconds remaining: " +  millisUntilFinished / 1000);
        }
        Toast.makeText(myContext, "Timer", Toast.LENGTH_SHORT).show();
    }

这是我的服务：

public class TimerService extends Service {
    private final static String TAG = "TimerService";
    public static final String TIMER_BR = "parking.group6.csc413.projectmap_timer";
    Intent timer_intent = new Intent(TIMER_BR);
    CountDownTimer cdt = null;

    @Override
    public void onCreate() {
        super.onCreate();
        Log.i(TAG, "Starting timer...");
        cdt = new CountDownTimer(30000, 1000) {
            @Override
            public void onTick(long millisUntilFinished) {
                Log.i(TAG, "Countdown seconds remaining: " + millisUntilFinished / 1000);
                timer_intent.putExtra("countdown", millisUntilFinished);
                sendBroadcast(timer_intent);
            }

            @Override
            public void onFinish() {
                Log.i(TAG, "Timer finished");
            }
        };

        cdt.start();
    }

    @Override
    public void onDestroy() {

        cdt.cancel();
        Log.i(TAG, "Timer cancelled");
        super.onDestroy();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

是的，我的清单文件有：

<service android:name=".TimerService"/>

Answer 1

仅当服务已启动或已在运行时，ComponentName才为空。如果该服务尚不存在，则返回null。要启动CountDownTimer，您可以使用操作：

Intent intent = new Intent(getActivity(), TimerService.class);
intent.setAction("START");
getActivity().startService(intent);

调用onStartCommand时，请检查操作是否等于START。如果是，请启动CountDownTimer

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    if ("START".equals(intent.getAction()) {
        // start CountDownTimer
    }
    return super.onStartCommand(intent, flags, startId);
}

StartService返回null Android Service

1 个答案: