Android - While loop crashing app - Contact List

Question

I'm building a Phoning App, where I can either type the number, or select a name and get the number.

It succeeds on getting the number into the Label, but if I "Go back/Cancel" the contact list, It crashes. I'm pretty sure it's the while loop, but I can't figure it out.

Here's the "Get Number" code:

public void onActivityResult(int reqCode, int resultCode, Intent data) {
      Uri uri = data.getData();

    Cursor cursor=this.getContentResolver().query(uri, null, null, null, null);

         while (cursor.moveToNext()) { 
         String contactId = cursor.getString(cursor.getColumnIndex( 
           ContactsContract.Contacts._ID)); 
         String hasPhone = cursor.getString(cursor.getColumnIndex( 
           ContactsContract.Contacts.HAS_PHONE_NUMBER)); 
         if (Integer.parseInt(cursor.getString( cursor.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0) { 
                      // You now have the number so now query it like this
      Cursor phones = getContentResolver().query( 
        ContactsContract.CommonDataKinds.Phone.CONTENT_URI, 
        null, 
        ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = "+ contactId, 
            null, null); 
          while (phones.moveToNext()) { 
          String phoneNumber = phones.getString( 
             phones.getColumnIndex( 
               ContactsContract.CommonDataKinds.Phone.NUMBER));  
          numberfield.setText(phoneNumber);
           } 
          phones.close();  
      }
 }

}

Whole .Java Code

public class Tabs extends Activity implements OnClickListener, OnLongClickListener{
    TabHost th;
TabSpec specs;
TextView numberfield;
public String string;
public String number;
//public String phoneNumber;
@Override
protected void onCreate(Bundle savedInstanceState){
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.tabs);
    th = (TabHost)findViewById(R.id.tabhost);
    numberfield = (TextView) findViewById(R.id.etNumberField);
    Button n1 = (Button) findViewById (R.id.bNumber1);
    Button n2 = (Button) findViewById (R.id.bNumber2);
    Button n3 = (Button) findViewById (R.id.bNumber3);
    Button n4 = (Button) findViewById (R.id.bNumber4);
    Button n5 = (Button) findViewById (R.id.bNumber5);
    Button n6 = (Button) findViewById (R.id.bNumber6);
    Button n7 = (Button) findViewById (R.id.bNumber7);
    Button n8 = (Button) findViewById (R.id.bNumber8);
    Button n9 = (Button) findViewById (R.id.bNumber9);
    Button nstar = (Button) findViewById (R.id.bNumberStar);
    Button n0 = (Button) findViewById (R.id.bNumber0);
    Button nhash = (Button) findViewById (R.id.bNumberHash);
    Button call = (Button) findViewById (R.id.bCall);
    Button sms = (Button) findViewById (R.id.bSMS);
    Button clear = (Button) findViewById (R.id.bClear);
    Button contact = (Button) findViewById (R.id.bContact);

    n1.setOnClickListener(this);
    n2.setOnClickListener(this);
    n3.setOnClickListener(this);
    n4.setOnClickListener(this);
    n5.setOnClickListener(this);
    n6.setOnClickListener(this);
    n7.setOnClickListener(this);
    n8.setOnClickListener(this);
    n9.setOnClickListener(this);
    nstar.setOnClickListener(this);
    n0.setOnClickListener(this);
    n0.setOnLongClickListener(this);
    nhash.setOnClickListener(this);
    call.setOnClickListener(this);
    clear.setOnClickListener(this);
    clear.setOnLongClickListener(this);
    sms.setOnClickListener(this);
    contact.setOnClickListener(this);

    th.setup();
    specs = th.newTabSpec("tag1");
    specs.setContent(R.id.Recents);
    specs.setIndicator("Recents");
    th.addTab(specs);

    specs = th.newTabSpec("tag2");
    specs.setContent(R.id.Keypad);
    specs.setIndicator("Keypad");
    th.addTab(specs);

    specs = th.newTabSpec("tag3");
    specs.setContent(R.id.Sms);
    specs.setIndicator("SMS");
    th.addTab(specs);

    specs = th.newTabSpec("tag4");
    specs.setContent(R.id.Ratings);
    specs.setIndicator("Ratings");
    th.addTab(specs);

    specs = th.newTabSpec("tag5");
    specs.setContent(R.id.Account);
    specs.setIndicator("Account");
    th.addTab(specs);
}
@Override
public void onClick(View arg0) {
    // TODO Auto-generated method stub
    switch(arg0.getId()){
    case R.id.bNumber1:
        numberfield.setText(numberfield.getText() + "1");
        break;
    case R.id.bNumber2:
        numberfield.setText(numberfield.getText() + "2");
        break;
    case R.id.bNumber3:
        numberfield.setText(numberfield.getText() + "3");
        break;
    case R.id.bNumber4:
        numberfield.setText(numberfield.getText() + "4");
        break;
    case R.id.bNumber5:
        numberfield.setText(numberfield.getText() + "5");
        break;
    case R.id.bNumber6:
        numberfield.setText(numberfield.getText() + "6");
        break;
    case R.id.bNumber7:
        numberfield.setText(numberfield.getText() + "7");
        break;
    case R.id.bNumber8:
        numberfield.setText(numberfield.getText() + "8");
        break;
    case R.id.bNumber9:
        numberfield.setText(numberfield.getText() + "9");
        break;
    case R.id.bNumberStar:
        numberfield.setText(numberfield.getText() + "*");
        break;
    case R.id.bNumber0:
        numberfield.setText(numberfield.getText() + "0");
        break;
    case R.id.bNumberHash:
        numberfield.setText(numberfield.getText() + "#");
        break;

    case R.id.bClear:
        String number = numberfield.getText().toString();
        if(number.length() > 0){
            String newNumber = number.substring(0, number.length()-1);
                    numberfield.setText(newNumber);
        }

        break;
    case R.id.bCall:
        call();

        break;
    case R.id.bContact:
         Intent intent = new Intent(Intent.ACTION_PICK, ContactsContract.Contacts.CONTENT_URI);
          startActivityForResult(intent, 1);   


    }
}
private void call() {
    // TODO Auto-generated method stub
    String number = numberfield.getText().toString();
    if(number.length() > 0){
    try {
           Intent callIntent = new Intent(Intent.ACTION_CALL);

            string = numberfield.getText().toString().trim();
               number = "tel:" + string;
            callIntent.setData(Uri.parse(number));
            startActivity(callIntent);


        } catch (ActivityNotFoundException activityException) {
             Log.e("helloandroid dialing example", "Call failed");
        }
    }
}
@Override
public boolean onLongClick(View arg0) {
    // TODO Auto-generated method stub
    switch(arg0.getId()){
    case R.id.bClear:

    numberfield.setText("");
    break;
    case R.id.bNumber0:

        numberfield.setText(numberfield.getText() + "+");

        break;
    }
    return true;

}

public void onActivityResult(int reqCode, int resultCode, Intent data) {
      Uri uri = data.getData();

    Cursor cursor=this.getContentResolver().query(uri, null, null, null, null);

         while (cursor.moveToNext()) { 
         String contactId = cursor.getString(cursor.getColumnIndex( 
           ContactsContract.Contacts._ID)); 
         String hasPhone = cursor.getString(cursor.getColumnIndex( 
           ContactsContract.Contacts.HAS_PHONE_NUMBER)); 
         if (Integer.parseInt(cursor.getString( cursor.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0) { 
                      // You now have the number so now query it like this
      Cursor phones = getContentResolver().query( 
        ContactsContract.CommonDataKinds.Phone.CONTENT_URI, 
        null, 
        ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = "+ contactId, 
            null, null); 
          while (phones.moveToNext()) { 
          String phoneNumber = phones.getString( 
             phones.getColumnIndex( 
               ContactsContract.CommonDataKinds.Phone.NUMBER));  
          numberfield.setText(phoneNumber);
           } 
          phones.close(); 


         }


}

}

}

Logcat:

Full Sized Logcat

Thanks in advance! Really Appriciated

Answer 1

You must check the if resultCode is RESULT_OK before going further. Your onActivityResult method should be something like this

public void onActivityResult(int reqCode, int resultCode, Intent data) {

        if(resultCode == RESULT_OK && data != null) {
            Uri uri = data.getData();

            Cursor cursor=this.getContentResolver().query(uri, null, null, null, null);

            while (cursor.moveToNext()) { 
                String contactId = cursor.getString(cursor.getColumnIndex( 
                        ContactsContract.Contacts._ID)); 
                String hasPhone = cursor.getString(cursor.getColumnIndex( 
                        ContactsContract.Contacts.HAS_PHONE_NUMBER)); 
                if (Integer.parseInt(cursor.getString( cursor.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0) { 
                    // You now have the number so now query it like this
                    Cursor phones = getContentResolver().query( 
                            ContactsContract.CommonDataKinds.Phone.CONTENT_URI, 
                            null, 
                            ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = "+ contactId, 
                            null, null); 
                    while (phones.moveToNext()) { 
                        String phoneNumber = phones.getString( 
                                phones.getColumnIndex( 
                                        ContactsContract.CommonDataKinds.Phone.NUMBER));  
                        numberfield.setText(phoneNumber);
                    } 
                    phones.close(); 


                }
            }

        }
    }

For more info about onActivityResult you can refer this : onActivityResult

Answer 2

When the user cancels an activity that you started for a result it still calls onActivityResult, but the data will be null. You're getting a null pointer exception inside onActivityResult because you try dereference the null data. You need to check resultCode and skip processing the data if the activity was cancelled.

if (resultCode == RESULT_CANCELED) {
    // respond appropriately
}

edit: To clarify, RESULT_CANCELED is a constant defined in Activity.