android - How detect incoming call

Can you tell me please where can i found more details about how can i call the methods that include these source code from the android's API so that i can develop new operations with them?

MainActivity.java
--------------------
package com.bitgriff.androidcalls;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

/**
* Main activity, with button to toggle phone calls detection on and off.
*
*/
public class MainActivity extends Activity {

private boolean detectEnabled;

private TextView textViewDetectState;
private Button buttonToggleDetect;
private Button buttonExit;

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

textViewDetectState = (TextView) findViewById(R.id.textViewDetectState);

buttonToggleDetect = (Button) findViewById(R.id.buttonDetectToggle);
buttonToggleDetect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
setDetectEnabled(!detectEnabled);
}
});

buttonExit = (Button) findViewById(R.id.buttonExit);
buttonExit.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
setDetectEnabled(false);
MainActivity.this.finish();
}
});
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}

private void setDetectEnabled(boolean enable) {
detectEnabled = enable;

Intent intent = new Intent(this, CallDetectService.class);
if (enable) {
// start detect service
startService(intent);

buttonToggleDetect.setText("Turn off");
textViewDetectState.setText("Detecting");
}
else {
// stop detect service
stopService(intent);

buttonToggleDetect.setText("Turn on");
textViewDetectState.setText("Not detecting");
}
}

}
CallDetectService.java
-----------------------
package com.bitgriff.androidcalls;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

/**
* Call detect service.
* This service is needed, because MainActivity can lost it's focus,
* and calls will not be detected.
*
*/
public class CallDetectService extends Service {
private CallHelper callHelper;

public CallDetectService() {
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
callHelper = new CallHelper(this);

int res = super.onStartCommand(intent, flags, startId);
callHelper.start();
return res;
}

@Override
public void onDestroy() {
super.onDestroy();

callHelper.stop();
}

@Override
public IBinder onBind(Intent intent) {
// not supporting binding
return null;
}
}
CallHelper.java
----------------
package com.bitgriff.androidcalls;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.widget.Toast;

/**
* Helper class to detect incoming and outgoing calls.
*
*/
public class CallHelper {

/**
* Listener to detect incoming calls.
*/
private class CallStateListener extends PhoneStateListener {
@Override
public void onCallStateChanged(int state, String incomingNumber) {
switch (state) {
case TelephonyManager.CALL_STATE_RINGING:
// called when someone is ringing to this phone

Toast.makeText(ctx,
"Incoming: "+incomingNumber,
Toast.LENGTH_LONG).show();
break;
}
}
}

/**
* Broadcast receiver to detect the outgoing calls.
*/
public class OutgoingReceiver extends BroadcastReceiver {
public OutgoingReceiver() {
}

@Override
public void onReceive(Context context, Intent intent) {
Str

in start has a text NOT DETECTING
after that it haw 2 buttons
the first is - Turn on
and the last is - exit

when i press Turn on the button message become turn off and the starting message become DETECTING
Finally when i press exit the starting message become NOT DETECTING and the app is exit.

i run this code on simulator so i don't know if the output was different if i had device..