我想將Note_On消息發(fā)送到名為LoopBe（鏈接到站點(diǎn)）的虛擬Midi接口。如何獲取Receiver對(duì)象（Java）？我嘗試了下面的代碼，但在上收到了NullPointerException rcvr.send()。public class test {public static Receiver rcvr;public static void main(String[] args) throws InvalidMidiDataException, MidiUnavailableException {    String scene = "Test";    getReceiver();    ShortMessage myMsg = new ShortMessage();    // Nachricht Channel Note Lautst?rke    myMsg.setMessage(ShortMessage.NOTE_ON, 0, 1, 127);    rcvr.send(myMsg, -1);    System.out.println("Szene " + scene + " ausgel?st");}public static void getReceiver() throws MidiUnavailableException {    MidiDevice.Info[] infos = MidiSystem.getMidiDeviceInfo();    for(Info devices : infos )    {        System.out.println(devices.getName() + " : " + devices.getDescription());        if(devices.getName() == "LoopBe Internal MIDI" && devices.getDescription() == "No details available") {            MidiDevice device = MidiSystem.getMidiDevice(devices);             rcvr =  device.getReceiver();            System.out.println("Receiver: " + rcvr.toString());        }    }  }}我嘗試了rcvr = MidiSystem.getReceiver()一下，但效果很好，但是它將消息發(fā)送到com.sun.media.sound.MidiOutDevice$MidiOutReceiver@404b9385。