How to call services using unlock event in Android?

Question

I like to make the application start service while user unlock his phone.When I start unlock phone, there is happen nothing, and when I login the application(after login, it will runs ThirdActivity.java), the application is force stopped.The error log has shown as following:

11-28 14:28:52.846: E/AndroidRuntime(6439): FATAL EXCEPTION: main
11-28 14:28:52.846: E/AndroidRuntime(6439): java.lang.RuntimeException: Unable to start  activity    ComponentInfo{com.example.android.project/com.example.android.project.ThirdActivity}:   java.lang.NullPointerException: println needs a message
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2205)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2240)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.app.ActivityThread.access$600(ActivityThread.java:139)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1262)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.os.Looper.loop(Looper.java:156)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.app.ActivityThread.main(ActivityThread.java:4987)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at java.lang.reflect.Method.invokeNative(Native Method)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at java.lang.reflect.Method.invoke(Method.java:511)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at dalvik.system.NativeStart.main(Native Method)
11-28 14:28:52.846: E/AndroidRuntime(6439): Caused by: java.lang.NullPointerException: println needs a message
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.util.Log.println_native(Native Method)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.util.Log.d(Log.java:138)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at com.example.android.project.ThirdActivity.onCreate(ThirdActivity.java:52)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.app.Activity.performCreate(Activity.java:4538)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1071)
11-28 14:28:52.846: E/AndroidRuntime(6439):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2161)
11-28 14:28:52.846: E/AndroidRuntime(6439):     ... 11 more

Before I add the codes following, it runs as usual:

    intentFilter = new IntentFilter();
    intentFilter.addAction(MyService.MY_ACTION);
    registerReceiver(intentReceiver, intentFilter);

    private BroadcastReceiver intentReceiver = new BroadcastReceiver() {...};
    protected void displayNotification(){...}

Anyone has any advice for this problem?

Here is StartMyServiceAtBootReceiver.java

public class StartMyServiceAtBootReceiver extends BroadcastReceiver{

    public void onReceive(Context context, Intent intent) {
          if (intent.getAction().equals(Intent.ACTION_USER_PRESENT)) {
                 HttpTest(context);                             
           }
     }

    public static boolean isNetworkAvailable( Context startMyServiceAtBootReceiver ) {
        Context context = startMyServiceAtBootReceiver.getApplicationContext();
        ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connectivity == null) {
        return false;
        } else {
        NetworkInfo[] info = connectivity.getAllNetworkInfo();
        if (info != null) {
        for (int i = 0; i < info.length; i++) {
        if (info[i].getState() == NetworkInfo.State.CONNECTED) {
        return true;
        }
        }
        }
        }
        return false;
        } 

    public static void HttpTest( final Context startMyServiceAtBootReceiver)
    {
    if(isNetworkAvailable( startMyServiceAtBootReceiver) ){

         Intent start = new Intent(startMyServiceAtBootReceiver, MyService.class);
         start.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
         startMyServiceAtBootReceiver.startService(start);
    }
    }

  }

MyService.java

public class MyService extends Service{

int counter = 0;
static final int UPDATE_INTERVAL = 15000;
private Timer timer = new Timer();
DefaultHttpClient httpclient;
HttpPost httppost;
String line,result;
HttpResponse response;
InputStream is;
BufferedReader reader;
StringBuilder sb;
final static String MY_ACTION = "MY_ACTION";

@Override
public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub
    return null;
}


public int onStartCommand(Intent intent, int flags, int startId){
    doSomethingRepeatedly();
    return START_STICKY;        
}

private void doSomethingRepeatedly(){
    timer.scheduleAtFixedRate(new TimerTask(){
        public void run(){
        //  Log.d("MyService", String.valueOf(++counter));
            try{
             httpclient = new DefaultHttpClient();
                httppost = new HttpPost("http://www.kryptoquest.com/testing/checking.php");
                response = httpclient.execute(httppost);
                is = response.getEntity().getContent();
        }catch(Exception e){
            Log.e("log_tag", "Error:"+e.toString());
        }

        //convert response to string
        try{
                    reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
                sb = new StringBuilder();
                line = null;
                while ((line = reader.readLine()) != null) {

                        sb.append(line + "\n");

                }
                Log.d("test",sb.toString());
                is.close();

                result = sb.toString();

             Intent intent = new Intent();
             intent.setAction(MY_ACTION);

             intent.putExtra("DATAPASSED", result);

             sendBroadcast(intent);


        }catch(Exception e){
                Log.e("log_tag", "Error converting result "+e.toString());
        }
        }
    },10000,UPDATE_INTERVAL);
}




public void onDestroy(){
    super.onDestroy();

    if(timer != null){
        timer.cancel();
    }

    Toast.makeText(this, "Service Destroyed", Toast.LENGTH_SHORT).show();
}

  }

ThirdActivity.java

public class ThirdActivity extends ListActivity{
Bundle b;
String user,line,result,datapassed;
DefaultHttpClient httpclient;
HttpPost httppost;
HttpResponse response;
InputStream is = null;
BufferedReader reader;
StringBuilder sb;
ArrayList<NameValuePair> nameValuePairs;
ListView lv;
IntentFilter intentFilter;
int notification = 1;
String str = "";
String[] data;
int dlength;


public void onCreate(Bundle savedInstancesState){
    super.onCreate(savedInstancesState);
    setContentView(R.layout.list_screen);
    lv = (ListView) findViewById(android.R.id.list);
    Log.d("dg",user);
    getList();
    intentFilter = new IntentFilter();
    intentFilter.addAction(MyService.MY_ACTION);
    registerReceiver(intentReceiver, intentFilter);
    user = getIntent().getExtras().getString("user");
}

    public void getList(){
    new Thread(){
        public void run(){
            try{
                 httpclient = new DefaultHttpClient();
                 httppost = new HttpPost("http://www.kryptoquest.com/tracker/friendlist.php");
                 response = httpclient.execute(httppost);
                 is = response.getEntity().getContent();
            }catch(Exception e){
                Log.e("log_tag", "Error:"+e.toString());
            }

            //convert response to string
            try{
                    reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
                    sb = new StringBuilder();
                    line = null;
                    while ((line = reader.readLine()) != null) {

                            sb.append(line + "\n");

                    }
                    Log.d("test",sb.toString());
                    is.close();

                    result = sb.toString();

                    final String[] friend = result.split("[*]");

                    runOnUiThread(new Runnable()
                    {
                        public void run(){                              
                            setListAdapter(new ArrayAdapter<String>(ThirdActivity.this,android.R.layout.simple_list_item_1,friend)); 
                        }
                    });


            }catch(Exception e){
                    Log.e("log_tag", "Error converting result "+e.toString());
            }
        }
    }.start();
}

 private BroadcastReceiver intentReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
        datapassed = intent.getStringExtra("DATAPASSED");
        if(datapassed.length()>0){

            data = datapassed.split("[*]");
            dlength = data.length;

            for(int i=0;i<dlength;i++){
                if(i==dlength-1){
                    str += String.valueOf(data[i]);                 
                }else{
                    str += String.valueOf(data[i]) + ",";
                }   
            }
            Log.d("dataServices",str);
            displayNotification();
                str = "";           
        }
        }
        };

        protected void displayNotification(){
            Intent i = new Intent(this,NotificationView.class);
            i.putExtra("notification", notification);
            i.putExtra("name",str);
            Log.d("String",str);
            PendingIntent pi = PendingIntent.getActivity(this, 0, i, PendingIntent.FLAG_UPDATE_CURRENT);

            NotificationManager mnotis =(NotificationManager)getSystemService(NOTIFICATION_SERVICE);

            Notification notis = new Notification(R.drawable.notices2,"Reminder:You have " + dlength + " new friend request",System.currentTimeMillis());
            notis.setLatestEventInfo(this,"Friend Request", str + "has sent you a friend request",pi);
            notis.vibrate = new long[]{100,250,100,500};
            mnotis.notify(0, notis);
        }
           }

Answer 1

In the onCreate() you have this line Log.d("dg",user); at this line user variable would always be null since you area assigning the value at the end of the onCreate() method. Move this line to end of the onCreate() method and also check for null value, only call the log.d if the value is not null..