How to check when an app calls you

import android.app.Activity;
import android.os.Bundle;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.widget.Toast;

public class PhoneListenerTestActivity extends Activity {

    PhoneStateCheckListener phoneCheckListener;



    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);



        phoneCheckListener = new PhoneStateCheckListener(this);



        TelephonyManager telephonyManager  =

(TelephonyManager)getSystemService(TELEPHONY_SERVICE); 

        telephonyManager.listen(phoneCheckListener,

PhoneStateListener.LISTEN_CALL_STATE); 

    }



    public class PhoneStateCheckListener extends PhoneStateListener {

        PhoneListenerTestActivity mainActivity;

        PhoneStateCheckListener(PhoneListenerTestActivity _main){

            mainActivity = _main;

        }


    @Override

    public void onCallStateChanged(int state, String incomingNumber) {

    if (state == TelephonyManager.CALL_STATE_IDLE) {

    Toast.makeText(mainActivity,"STATE_IDLE : Incoming number " 

+ + incomingNumber,Toast.LENGTH_SHORT).show();

    } } else if (state == TelephonyManager.CALL_STATE_RINGING) {

    Toast.makeText(mainActivity,"STATE_RINGING : Incoming number "

 + + incomingNumber,Toast.LENGTH_SHORT).show();

//This is the receiving part.

    } } else if (state == TelephonyManager.CALL_STATE_OFFHOOK) {

        Toast.makeText(mainActivity,"STATE_OFFHOOK : Incoming number " 

+ + incomingNumber,Toast.LENGTH_SHORT).show();

    }

    }

    }     

}