MidiDevice (Java Platform SE 8 )
Keywords: javax.sound.midi.MidiDevice interface
Date: 2016-04-24

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-dependant 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 and 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

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and 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 The returned transmitter must be closed when the application has finished using it.
    `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 Detail

    - #### 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

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