If the creation of this Receiver resulted in implicitly opening the underlying device, the device is implicitly closed by this method. This is true unless the device is kept open by other Receiver or Transmitter instances that opened the device implicitly, and unless the device has been opened explicitly. If the device this Receiver is retrieved from is closed explicitly by calling MidiDevice.close , the Receiver is closed, too. For a detailed description of open/close behaviour see the class description of MidiDevice .