why i can't start my service when the android startup ? ( code attached )

Question

I trying to write simple basic application that will start my service when the phone is start.

i add all the permission i need.

I install the application on my android ( android 6.01 ). And when i reboot my phone - i can't see that the service is up or did any action.

1. why this is not working ?
2. how can i debug a service on android ?

The code:

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAG" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/Theme.AppCompat.NoActionBar">

    <service android:name=".MyService" android:enabled="true" android:exported="true"/>

    <receiver android:name=".MainBroadcastReceiver" android:enabled="true" android:exported="true" >
        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED"/>
        </intent-filter>
    </receiver>
</application>



public class MainBroadcastReceiver extends BroadcastReceiver {
    public MainBroadcastReceiver(){

    }

    @Override
    public void onReceive(Context context, Intent intent) {
        context.startService(new Intent(context, MyService.class));
    }
}




public class MyService extends Service {

private File _file;
private Timer _timer;
private FileOutputStream _fileOutputStream;

public MyService() throws IOException {

    _file = new File("/sdcard/" + "myServiceText.txt");
    _file.createNewFile();

    _fileOutputStream = openFileOutput(_file.getName(), Context.MODE_APPEND);
    _fileOutputStream.write("Ctor called".getBytes());
}

@Override
public IBinder onBind(Intent arg0) {
    return null;
}


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

    _timer = new Timer("timer");
    _timer.schedule(new TimerTask()
    {
        @Override
        public void run()
        {
            try {
                _fileOutputStream.write("onCreate Called".getBytes());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }, 0, 5000);

}

@Override
public void onDestroy() {
    super.onDestroy();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    try {
        _fileOutputStream.write("onStartCommand".getBytes());
    } catch (IOException e) {
        e.printStackTrace();
    }
    return START_STICKY;
}

Answer 1

Your code is fine, the reason your service is not running it's because your app is in Stopped State.

1. Stopped state is a security procedure that allows your app to "wake itself up" only after user first manually launches it from the home screen.(Unless you are a system)
By doing so android prevents malicious apps to be installed and run in your phone background without you knowing.

2. How to debug a background process?
When working with background processes there are two great tools you need in your belt -
First is the adb broadcast command -
adb shell am broadcast -a android.intent.action.BOOT_COMPLETED

Second is attach remote debugger (Android Studio):
Run | Attach debugger to android process (last option in the menu) | choose your app's process.