GCM and android Async Exception

Question

I have been trying to work with GCM for android,the project was working fine initially and then all of a sudden I have been getting this error and I haven't been able to figure it out.

Main Activity Class

package com.example.googlecloudmessaging;

import java.io.IOException;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

import com.google.android.gms.gcm.GoogleCloudMessaging;

public class MainActivity extends Activity implements OnClickListener {

Button btnRegId;
EditText etRegId;
GoogleCloudMessaging gcm;
String regid;
String PROJECT_NUMBER = "xxxxxxx";

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

    btnRegId = (Button) findViewById(R.id.button_get_id);
    etRegId = (EditText) findViewById(R.id.edit_text_id);

    btnRegId.setOnClickListener(this);
}

public void getRegId() {
    new AsyncTask<Void, Void, String>() {

        @Override
        protected String doInBackground(Void... params) {
            String msg = "";

            try {


                if(gcm==null)
                gcm = GoogleCloudMessaging
                        .getInstance(getApplicationContext());
                regid = gcm.register("PROJECT_NUMBER");
                msg = "Device registered, registration ID=" + regid;
                Log.i("GCM", "!!!!! " + regid);

            } catch (IOException ex) {
                msg = "Error: " + ex.getMessage();
            }
            return msg;
        }

        @Override
        protected void onPostExecute(String msg) {
                etRegId.setText(msg + "\n");

        }
    }.execute(null, null, null);
}

@Override
public void onClick(View v) {
    getRegId();
}

}

Error

07-16 15:47:04.453: E/AndroidRuntime(1745): FATAL EXCEPTION: AsyncTask #1
07-16 15:47:04.453: E/AndroidRuntime(1745): Process: com.example.googlecloudmessaging, PID: 1745
07-16 15:47:04.453: E/AndroidRuntime(1745): java.lang.RuntimeException: An error occured while executing doInBackground()
07-16 15:47:04.453: E/AndroidRuntime(1745): at android.os.AsyncTask$3.done(AsyncTask.java:304)
07-16 15:47:04.453: E/AndroidRuntime(1745): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
07-16 15:47:04.453: E/AndroidRuntime(1745): at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
07-16 15:47:04.453: E/AndroidRuntime(1745): at java.util.concurrent.FutureTask.run(FutureTask.java:242)
07-16 15:47:04.453: E/AndroidRuntime(1745): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
07-16 15:47:04.453: E/AndroidRuntime(1745): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
07-16 15:47:04.453: E/AndroidRuntime(1745): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
07-16 15:47:04.453: E/AndroidRuntime(1745): at java.lang.Thread.run(Thread.java:818)
07-16 15:47:04.453: E/AndroidRuntime(1745): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.contains(java.lang.CharSequence)' on a null object reference
07-16 15:47:04.453: E/AndroidRuntime(1745): at com.google.android.gms.gcm.GoogleCloudMessaging.register(Unknown Source)
07-16 15:47:04.453: E/AndroidRuntime(1745): at com.example.googlecloudmessaging.MainActivity$1.doInBackground(MainActivity.java:50)
07-16 15:47:04.453: E/AndroidRuntime(1745): at com.example.googlecloudmessaging.MainActivity$1.doInBackground(MainActivity.java:1)
07-16 15:47:04.453: E/AndroidRuntime(1745): at android.os.AsyncTask$2.call(AsyncTask.java:292)
07-16 15:47:04.453: E/AndroidRuntime(1745): at java.util.concurrent.FutureTask.run(FutureTask.java:237)
07-16 15:47:04.453: E/AndroidRuntime(1745):     ... 4 more

Answer 1

GoogleCloudMessaging register and unregister methods are deprecated. I guess you should use InstanceID.getToken().