user2652614 user2652614 - 11 days ago 8
Android Question

Local Broadcast null pointer exception

I have a local broadcast inside an intentService which sends a message to an activity. the problem is am getting a null pointer exception. any help is appreciated :)

LogCat Error

01-22 17:57:15.461: I/Arrival(16592): This is instantated
01-22 17:57:16.859: D/sender(16592): Broadcasting message
01-22 17:57:16.867: D/AndroidRuntime(16592): Shutting down VM
01-22 17:57:16.867: W/dalvikvm(16592): threadid=1: thread exiting with uncaught exception (group=0x4110d930)
01-22 17:57:16.875: E/AndroidRuntime(16592): FATAL EXCEPTION: main
01-22 17:57:16.875: E/AndroidRuntime(16592): java.lang.NullPointerException
01-22 17:57:16.875: E/AndroidRuntime(16592): at android.support.v4.content.LocalBroadcastManager.executePendingBroadcasts(LocalBroadcastManager.java:297)
01-22 17:57:16.875: E/AndroidRuntime(16592): at android.support.v4.content.LocalBroadcastManager.access$000(LocalBroadcastManager.java:46)
01-22 17:57:16.875: E/AndroidRuntime(16592): at android.support.v4.content.LocalBroadcastManager$1.handleMessage(LocalBroadcastManager.java:116)
01-22 17:57:16.875: E/AndroidRuntime(16592): at android.os.Handler.dispatchMessage(Handler.java:99)
01-22 17:57:16.875: E/AndroidRuntime(16592): at android.os.Looper.loop(Looper.java:175)
01-22 17:57:16.875: E/AndroidRuntime(16592): at android.app.ActivityThread.main(ActivityThread.java:5279)
01-22 17:57:16.875: E/AndroidRuntime(16592): at java.lang.reflect.Method.invokeNative(Native Method)
01-22 17:57:16.875: E/AndroidRuntime(16592): at java.lang.reflect.Method.invoke(Method.java:511)
01-22 17:57:16.875: E/AndroidRuntime(16592): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
01-22 17:57:16.875: E/AndroidRuntime(16592): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
01-22 17:57:16.875: E/AndroidRuntime(16592): at dalvik.system.NativeStart.main(Native Method)


Receiver Class (Activity)

package com.user;

public class Arrival_List extends Activity {


SqlHandler sqlHandler;
ListView lvCustomList, listView;
EditText IconBearing, BusName, DistanceInfo;
Button btnGetData;

MediaPlayer mp;
String SENDER_ID = "616159599278";
static final String TAG = "GCMDemo";
GoogleCloudMessaging gcm;
TextView mDisplay;
Context context;
String regid;
private BroadcastReceiver mMessageReceiver;

ArrayList<ContactListItems> contactList = new ArrayList<ContactListItems>();
ContactListAdapter contactListAdapter = new ContactListAdapter(this,
contactList);

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_arrival);

sqlHandler = new SqlHandler(this);
btnMap = (Button) findViewById(R.id.OPEN_MAP);
RelativeLayout listViewHolder = (RelativeLayout) findViewById(R.id.listViewHolder);
lvCustomList = new ListView(getApplication());
listViewHolder.addView(lvCustomList);
Log.i("Arrival", "This is instantated");

LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
new IntentFilter("custom-event-name"));


// Our handler for received Intents. This will be called whenever an Intent
// with an action named "custom-event-name" is broadcasted.
mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// Get extra data included in the Intent
String message = intent.getStringExtra("message");
Log.i("receiver", "Got message: " + message);

}
};

}

@Override
protected void onDestroy() {
// Unregister since the activity is about to be closed.
LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
super.onDestroy();
}


}


Sender Class (Service)

public class Get_Distane_Data extends IntentService {

SqlHandler sqlHandler;
ListView lvCustomList, listView;
EditText IconBearing, BusName, DistanceInfo;
Button btnGetData;
JSONParser jsonParser = new JSONParser();
JSONArray products = null;
MediaPlayer mp;
String SENDER_ID = "616159599278";
static final String TAG = "GCMDemo";
GoogleCloudMessaging gcm;

TextView mDisplay;
Context context;
String regid;
private static String URL_Distance = "http://vu2150.admin.studentswebprojects.ritaj.ps/Distance_Send_Receive/Get_Distance_From_Database.php";
ArrayList<ContactListItems> contactList = new ArrayList<ContactListItems>();
ContactListAdapter contactListAdapter = new ContactListAdapter(this,
contactList);

public Get_Distane_Data() {
super("Get_Distane_Data");
}

@Override
protected void onHandleIntent(Intent intent) {
sqlHandler = new SqlHandler(this);
// TODO Auto-generated method stub
String RegistrartionID = RegisID();

List<NameValuePair> params = new ArrayList<NameValuePair>();

params.add(new BasicNameValuePair("RegistrartionID", RegistrartionID));

Log.i("RegistrartionID", RegistrartionID);

JSONObject json = jsonParser.makeHttpRequest(URL_Distance, "POST",
params);
String query = "DELETE FROM GPS_INFORMATION;";
sqlHandler.executeQuery(query);

try {
// Checking for SUCCESS TAG
int success = json.getInt("success");

if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray("products");

// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);

// Storing each json item in variable

String Bus_Distance = c.getString("Bus_Distance");

String Bus_Bearing = c.getString("Bus_Bearing");
String Bus_Long = c.getString("Bus_Long");
String Bus_Lat = c.getString("Bus_Lat");
String BusName = c.getString("Bus_Name");

Log.i("Bus_Distance", Bus_Distance);
Log.i("Bus_Bearing", Bus_Bearing);
Log.i("Bus_Long", Bus_Long);
Log.i("Bus_Lat", Bus_Lat);
Log.i("BusName", BusName);

try {
String query0 = "INSERT INTO GPS_INFORMATION(Bus_Name,Distance_Info,Icon_Bearing,Bus_Lat,Bus_Long) values ('"
+ Bus_Bearing
+ "','"
+ BusName
+ "','"
+ Bus_Distance
+ "','"
+ Bus_Lat
+ "','"
+ Bus_Long + "')";
sqlHandler.executeQuery(query0);

sendMessage();

} catch (Exception e) {
Log.i("error", "this is where the error happens");
}

}
}
} catch (JSONException e) {
e.printStackTrace();
}
}



private void sendMessage() {
Log.d("sender", "Broadcasting message");
Intent intent = new Intent("custom-event-name");
intent.putExtra("message", "This is my message!");
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}

}

Answer

in line

LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
              new IntentFilter("custom-event-name"));

mMessageReceiver is null, it is assigned below, you must initialize before registerReceiver