Android :: Check The Service With Some Name Running Once?

how to check that the service with some name is running once? also if i go out from my activity then my service is running & when i come to my activity the onCreate method is called so my service is created again in this case or running service will be attached again?

public class ServiceExampleActivity extends Activity { Intent intent; Button start,stop; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); intent = new Intent(this, ServiceExample.class); // service example is service class Log.i("-----service------", "Service Created"); }