Module java.desktop
Package javax.sound.midi

# Interface MidiDevice

All Superinterfaces:
  `AutoCloseable`

All Known Subinterfaces:
  `Sequencer`, `Synthesizer`

public interface MidiDevice extends AutoCloseable
`MidiDevice` is the base interface for all MIDI devices. Common devices include synthesizers, sequencers, MIDI input ports, and MIDI output ports.

A `MidiDevice` can be a transmitter or a receiver of MIDI events, or both. Therefore, it can provide `Transmitter` or `Receiver` instances (or both). Typically, MIDI IN ports provide transmitters, MIDI OUT ports and synthesizers provide receivers. A Sequencer typically provides transmitters for playback and receivers for recording.

A `MidiDevice` can be opened and closed explicitly as well as implicitly. Explicit opening is accomplished by calling `open()`, explicit closing is done by calling `close()` on the `MidiDevice` instance. If an application opens a `MidiDevice` explicitly, it has to close it explicitly to free system resources and enable the application to exit cleanly. Implicit opening is done by calling `MidiSystem.getReceiver()` and `MidiSystem.getTransmitter()`. The `MidiDevice` used by `MidiSystem.getReceiver` and `MidiSystem.getTransmitter` is implementation-dependent unless the properties `javax.sound.midi.Receiver` and `javax.sound.midi.Transmitter` are used (see the description of properties to select default providers in `MidiSystem`). A `MidiDevice` that was opened implicitly, is closed implicitly by closing the `Receiver` or `Transmitter` that resulted in opening it. If more than one implicitly opening `Receiver` or `Transmitter` were obtained by the application, the device is closed after the last `Receiver` or `Transmitter` has been closed. On the other hand, calling `getReceiver` or `getTransmitter` on the device instance directly does not open the device implicitly. Closing these `Transmitter`s and `Receiver`s does not close the device implicitly. To use a device with `Receiver`s or `Transmitter`s obtained this way, the device has to be opened and closed explicitly.

If implicit and explicit opening and closing are mixed on the same `MidiDevice` instance, the following rules apply:

- After an explicit open (either before or after implicit opens), the device will not be closed by implicit closing. The only way to close an explicitly opened device is an explicit close.
- An explicit close always closes the device, even if it also has been opened implicitly. A subsequent implicit close has no further effect.

To detect if a MidiDevice represents a hardware MIDI port, the following programming technique can be used:

     MidiDevice device = ...;
     if (!(device instanceof Sequencer) && !(device instanceof Synthesizer)) {
       // we're now sure that device represents a MIDI port
       // ...
     }

A `MidiDevice` includes a `MidiDevice.Info` object to provide manufacturer information and so on.

See Also:
  - `Synthesizer`
  - `Sequencer`
  - `Receiver`
  - `Transmitter`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Interface
  Description
  `static class`
  `MidiDevice.Info`
  A `MidiDevice.Info` object contains assorted data about a `MidiDevice`, including its name, the company who created it, and descriptive text.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `close()`
  Closes the device, indicating that the device should now release any system resources it is using.
  `MidiDevice.Info`
  `getDeviceInfo()`
  Obtains information about the device, including its Java class and `Strings` containing its name, vendor, and description.
  `int`
  `getMaxReceivers()`
  Obtains the maximum number of MIDI IN connections available on this MIDI device for receiving MIDI data.
  `int`
  `getMaxTransmitters()`
  Obtains the maximum number of MIDI OUT connections available on this MIDI device for transmitting MIDI data.
  `long`
  `getMicrosecondPosition()`
  Obtains the current time-stamp of the device, in microseconds.
  `Receiver`
  `getReceiver()`
  Obtains a MIDI IN receiver through which the MIDI device may receive MIDI data.
  `List<Receiver>`
  `getReceivers()`
  Returns all currently active, non-closed receivers connected with this `MidiDevice`.
  `Transmitter`
  `getTransmitter()`
  Obtains a MIDI OUT connection from which the MIDI device will transmit MIDI data.
  `List<Transmitter>`
  `getTransmitters()`
  Returns all currently active, non-closed transmitters connected with this `MidiDevice`.
  `boolean`
  `isOpen()`
  Reports whether the device is open.
  `void`
  `open()`
  Opens the device, indicating that it should now acquire any system resources it requires and become operational.

- ## Method Details

  - ### getDeviceInfo

    MidiDevice.Info getDeviceInfo()
    Obtains information about the device, including its Java class and `Strings` containing its name, vendor, and description.
    Returns:
      device info

  - ### open

    void open() throws MidiUnavailableException
    Opens the device, indicating that it should now acquire any system resources it requires and become operational.

    An application opening a device explicitly with this call has to close the device by calling `close()`. This is necessary to release system resources and allow applications to exit cleanly.

    Note that some devices, once closed, cannot be reopened. Attempts to reopen such a device will always result in a `MidiUnavailableException`.

    Throws:
      `MidiUnavailableException` - thrown if the device cannot be opened due to resource restrictions
      `SecurityException` - thrown if the device cannot be opened due to security restrictions
    See Also:
      - `close()`
      - `isOpen()`

  - ### close

    void close()
    Closes the device, indicating that the device should now release any system resources it is using.

    All `Receiver` and `Transmitter` instances open from this device are closed. This includes instances retrieved via `MidiSystem`.

    Specified by:
      `close` in interface `AutoCloseable`
    See Also:
      - `open()`
      - `isOpen()`

  - ### isOpen

    boolean isOpen()
    Reports whether the device is open.
    Returns:
      `true` if the device is open, otherwise `false`
    See Also:
      - `open()`
      - `close()`

  - ### getMicrosecondPosition

    long getMicrosecondPosition()
    Obtains the current time-stamp of the device, in microseconds. If a device supports time-stamps, it should start counting at 0 when the device is opened and continue incrementing its time-stamp in microseconds until the device is closed. If it does not support time-stamps, it should always return -1.
    Returns:
      the current time-stamp of the device in microseconds, or -1 if time-stamping is not supported by the device

  - ### getMaxReceivers

    int getMaxReceivers()
    Obtains the maximum number of MIDI IN connections available on this MIDI device for receiving MIDI data.
    Returns:
      maximum number of MIDI IN connections, or -1 if an unlimited number of connections is available

  - ### getMaxTransmitters

    int getMaxTransmitters()
    Obtains the maximum number of MIDI OUT connections available on this MIDI device for transmitting MIDI data.
    Returns:
      maximum number of MIDI OUT connections, or -1 if an unlimited number of connections is available

  - ### getReceiver

    Receiver getReceiver() throws MidiUnavailableException
    Obtains a MIDI IN receiver through which the MIDI device may receive MIDI data. The returned receiver must be closed when the application has finished using it.

    Usually the returned receiver implements the `MidiDeviceReceiver` interface.

    Obtaining a `Receiver` with this method does not open the device. To be able to use the device, it has to be opened explicitly by calling `open()`. Also, closing the `Receiver` does not close the device. It has to be closed explicitly by calling `close()`.

    Returns:
      a receiver for the device
    Throws:
      `MidiUnavailableException` - thrown if a receiver is not available due to resource restrictions
    See Also:
      - `Receiver.close()`

  - ### getReceivers

    List<Receiver> getReceivers()
    Returns all currently active, non-closed receivers connected with this `MidiDevice`. A receiver can be removed from the device by closing it.

    Usually the returned receivers implement the `MidiDeviceReceiver` interface.

    Returns:
      an unmodifiable list of the open receivers
    Since:
      1.5

  - ### getTransmitter

    Transmitter getTransmitter() throws MidiUnavailableException
    Obtains a MIDI OUT connection from which the MIDI device will transmit MIDI data. The returned transmitter must be closed when the application has finished using it.

    Usually the returned transmitter implements the `MidiDeviceTransmitter` interface.

    Obtaining a `Transmitter` with this method does not open the device. To be able to use the device, it has to be opened explicitly by calling `open()`. Also, closing the `Transmitter` does not close the device. It has to be closed explicitly by calling `close()`.

    Returns:
      a MIDI OUT transmitter for the device
    Throws:
      `MidiUnavailableException` - thrown if a transmitter is not available due to resource restrictions
    See Also:
      - `Transmitter.close()`

  - ### getTransmitters

    List<Transmitter> getTransmitters()
    Returns all currently active, non-closed transmitters connected with this `MidiDevice`. A transmitter can be removed from the device by closing it.

    Usually the returned transmitters implement the `MidiDeviceTransmitter` interface.

    Returns:
      an unmodifiable list of the open transmitters
    Since:
      1.5