public final ZMonitor start()
    {
        if (started) {
            System.out.println("ZMonitor: Unable to start while already started.");
            return this;
        }
        agent.send(START);
        agent.recv();
        started = true;
        return this;
    }
public final ZMonitor start ( ) { if ( started ) { System . out . println ( "ZMonitor: Unable to start while already started." ) ; return this ; } agent . send ( START ) ; agent . recv ( ) ; started = true ; return this ; }
Starts the monitoring.
Event types have to be added before the start, or they will take no effect.
@return this instance.