remove proximityAlert from different context

Question

I've created proximityAlarm in service called S.java

@Override
public int onStartCommand(Intent intent, int flags, int startId) {     

locPrefs = getSharedPreferences("locations", 0);
            String stringArray = locPrefs.getString("ssidArray", "");

            int locationCountP = locPrefs.getInt("locationCount", 0);

            final ArrayList<String> wifis = 
                    new ArrayList<String>(Arrays.asList(stringArray.split(",")));

            if(locationCountP!=0){
                if (wifis.contains(ssid)) {

                    if (prefs.getBoolean(PreferencesActivity.TOAST, false))
                        {
                            Toast.makeText(getBaseContext(), getString(R.string.wifiAlreadyAdded), Toast.LENGTH_SHORT).show();
                    }
                } else {
                    addProxAlert(lat, lng, locationCountP);
                    wifis.add(ssid);
                    if (prefs.getBoolean(PreferencesActivity.TOAST, false))
                        {
                            Toast.makeText(getBaseContext(), getString(R.string.newWifiAdded), Toast.LENGTH_SHORT).show();
                    }
                }
            } 

            else {
                addProxAlert(lat, lng, locationCountP);
                Toast.makeText(getBaseContext(), getString(R.string.firstWifiAdded), Toast.LENGTH_SHORT).show();
            }
        }   



public void addProxAlert(double lat, double lng, int id) {

    Intent pIntent = new Intent(PROX_ALERT_INTENT);
    Log.v("loc", Integer.toString(locationCountP-1));
    PendingIntent proximityIntent = PendingIntent.getBroadcast(getApplicationContext(), id, pIntent, Intent.FLAG_ACTIVITY_NEW_TASK);

    lm.addProximityAlert(lat, lng, 20, -1, proximityIntent);

    IntentFilter filter = new IntentFilter(PROX_ALERT_INTENT);
    registerReceiver(new ProximityIntentReceiver(), filter);
}

but i need to remove the same proximityAlarm from activity called A.java.

import android.app.Activity;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.SharedPreferences;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

public class WifiList extends Activity {

private LocationManager lm;
private static final String PROX_ALERT_INTENT = 
         "dado.pack";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.wifilist);

    final Button delete = (Button) findViewById(R.id.deletewifi);

    locPrefs = getSharedPreferences("locations", 0);
    int locationCount = locPrefs.getInt("locationCount", 0);

    final RadioGroup rg = (RadioGroup) findViewById(R.id.radioGroup1);
    rg.setOrientation(RadioGroup.VERTICAL);

    if(locationCount!=0){

        String ssid = "";
        Toast.makeText(getBaseContext(), Integer.toString(locationCount), Toast.LENGTH_SHORT).show();

        for(int i=0;i<locationCount;i++){

            ssid = locPrefs.getString("ssid"+i,"0");
            Log.v("i", Integer.toString(i));
            final RadioButton rb = new RadioButton(this);
            rb.setLayoutParams (new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
            rb.setText(ssid);
            rb.setId(i);
            rg.addView(rb, i);
        }

    }

    delete.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            int idbt = rg.getCheckedRadioButtonId();
            Log.v("id", Integer.toString(idbt));
            Intent pIntent = new Intent(PROX_ALERT_INTENT);
            PendingIntent proximityIntent = PendingIntent.getBroadcast(getApplicationContext(), idbt, pIntent, Intent.FLAG_ACTIVITY_NEW_TASK);
            lm.removeProximityAlert(proximityIntent);

        }
    });
}

NullPointerException on lm.removeProximityAlert(proximityIntent).

05-02 12:43:54.536: E/AndroidRuntime(32564): FATAL EXCEPTION: main
05-02 12:43:54.536: E/AndroidRuntime(32564): Process: dado.pack, PID: 32564  
05-02 12:43:54.536: E/AndroidRuntime(32564): java.lang.NullPointerException
05-02 12:43:54.536: E/AndroidRuntime(32564):    at dado.pack.WifiList$1.onClick(WifiList.java:64)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at android.view.View.performClick(View.java:4633)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at android.view.View$PerformClick.run(View.java:19330)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at android.os.Handler.handleCallback(Handler.java:733)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at android.os.Handler.dispatchMessage(Handler.java:95)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at android.os.Looper.loop(Looper.java:157)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at android.app.ActivityThread.main(ActivityThread.java:5356)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at java.lang.reflect.Method.invokeNative(Native Method)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at java.lang.reflect.Method.invoke(Method.java:515)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
05-02 12:43:54.536: E/AndroidRuntime(32564):    at dalvik.system.NativeStart.main(Native Method)

WHY??

tnx!!!

Answer 1

You wrote:

NullPointerException on lm.removeProximityAlert(proximityIntent)

because lm is null. You never initialize this member variable.