CODEWITHSUNDEEP
javaandroidandroid-intent
user4323984
user4323984

Reputation:

App crashes on Button Press stating "Attempt to invoke virtual method"

I have an android application which should opens an activity on button press, but when i click on itm the app crashes stating "Attempt to invoke virtual method". Here is my Code.

MainClass.java

public class MainActivity extends ActionBarActivity {
Button Notify;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Notify = (Button)findViewById(R.id.notify);

        Notify.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            Intent intent = new Intent(MainActivity.this, DisplayPush.class);
                startActivity(intent);


        }
    });
    }

My another activity class

DisplayPush.java

public class DisplayPush extends Activity {

@Override
public void onBackPressed(){
   Intent myIntent = new Intent(DisplayPush.this,MainActivity.class);
   startActivity(myIntent);
  //  overridePendingTransition(R.anim.from_middle, R.anim.to_middle);
    finish();
}

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

    TextView notification_title = (TextView) findViewById(R.id.title);
    TextView notification_message = (TextView) findViewById(R.id.message);

    ParseAnalytics.trackAppOpened(getIntent());

    Intent intent = getIntent();
    Bundle extras = intent.getExtras();
    String jsonData = extras.getString("com.parse.Data");

    try{
        JSONObject notification = new JSONObject(jsonData);
       // String title = notification.getString("push_hash");
        String message = notification.getString("alert");

      //  notification_title.setText(title);
        notification_message.setText(message);
    }
    catch(JSONException e){
        Toast.makeText(getApplicationContext(), "Something went wrong with the notification", Toast.LENGTH_SHORT).show();
    }

}

I have defined the acitivities in my manifest. Here is the logcat.

03-21 06:51:35.157: E/AndroidRuntime(3042): FATAL EXCEPTION: main
03-21 06:51:35.157: E/AndroidRuntime(3042): Process: hasan.parsereceiveandshow, PID: 3042
03-21 06:51:35.157: E/AndroidRuntime(3042): java.lang.RuntimeException: Unable to start activity ComponentInfo{hasan.parsereceiveandshow/hasan.parsereceiveandshow.DisplayPush}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference

Upvotes: 0

Views: 941

Answers (2)

ρяσѕρєя K
ρяσѕρєя K

Reputation: 132992

As in log:

Bundle.getString(java.lang.String)' on a null object reference

Because extras is null.

Not sending Bundle which contain com.parse.Data key with Intent which is used for starting DisplayPush Activity on Button Click.

What should i edit in code ?

Send data with com.parse.Data key in Intent on Notify Button click:

Intent intent = new Intent(MainActivity.this, DisplayPush.class);
intent.putExtra("com.parse.Data","String text");
startActivity(intent);

And also add null check before getting values from Bundle:

if(extras !=null)
  if(extras.containsKey("com.parse.Data"))
    String jsonData = extras.getString("com.parse.Data");

And define String jsonData; globally as said in comments.

Upvotes: 2

Mikhail
Mikhail

Reputation: 3746

The exception says that you're trying to call getString method on null reference. In DisplayPush you are getting Bundle object from intent which is null, because you didn't put any in your intent in onClick method in MainActivity class.

Upvotes: 1

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