Java Android：子类，来自主活动类的Call方法导致NullPointerException

Question

i want to call function from subclass to main activity class. here is my source code : SMS.java

public class SMS extends ListActivity {
    public void testerr(String kata) {
        Toast.makeText(getBaseContext(), "test coyyyy="+kata, Toast.LENGTH_LONG).show();
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        }
}

SMSReceiver.java

public class SmsReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Bundle bundle = intent.getExtras();
        SmsMessage[] msgs = null;
        String str = "";
        try {
            if (bundle != null) {
                Object[] pdus = (Object[]) bundle.get("pdus");
                msgs = new SmsMessage[pdus.length];
                for (int i = 0; i < msgs.length; i++) {
                    msgs[i] = SmsMessage.createFromPdu((byte[]) pdus[i]);
                    str += "SMS from " + msgs[i].getOriginatingAddress();
                    str += " :";
                    str += msgs[i].getMessageBody().toString();
                    str += "\n";
                }
                Toast.makeText(context, str, Toast.LENGTH_LONG).show();
                SMS sss = new SMS(); ---> call the main class
                sss.testerr("try the words"); ---> call method from main class
                Toast.makeText(context, str, Toast.LENGTH_LONG).show();
            }
        }
        catch(NullPointerException ex){
            Toast.makeText(context, "penyakite neng kene:"+ex.getMessage(), Toast.LENGTH_LONG).show();
        }
    }
}

my program run after it receive new text message, and i always get NullPointerException when call that sss.testerr("my example words"); any clue guys? thankyou so much for your help

Answer 1

You should not instantiate the Activity with it's constructor, either start it with an intent, or, if the Activity is already up, make it implement the broadcast receiver.

If you only want to show toast from your receiver, you can use the answer for this question