- All Implemented Interfaces:
Cloneable
- Direct Known Subclasses:
MetaMessage
,ShortMessage
,SysexMessage
MidiMessage
is the base class for MIDI messages. They include not
only the standard MIDI messages that a synthesizer can respond to, but also
"meta-events" that can be used by sequencer programs. There are meta-events
for such information as lyrics, copyrights, tempo indications, time and key
signatures, markers, etc. For more information, see the Standard MIDI Files
1.0 specification, which is part of the Complete MIDI 1.0 Detailed
Specification published by the MIDI Manufacturer's Association
(http://www.midi.org).
The base MidiMessage
class provides access to three types of
information about a MIDI message:
- The messages's status byte
- The total length of the message in bytes (the status byte plus any data bytes)
- A byte array containing the complete message
MidiMessage
includes methods to get, but not set, these values.
Setting them is a subclass responsibility.
The MIDI standard expresses MIDI data in bytes.
However, because Java uses signed bytes, the Java Sound API uses
integers instead of bytes when expressing MIDI data. For example, the
getStatus()
method of MidiMessage
returns MIDI status bytes
as integers. If you are processing MIDI data that originated outside Java
Sound and now is encoded as signed bytes, the bytes can be converted to
integers using this conversion:
int i = (int)(byte & 0xFF)
If you simply need to pass a known MIDI byte value as a method parameter, it
can be expressed directly as an integer, using (for example) decimal or
hexadecimal notation. For instance, to pass the "active sensing" status byte
as the first argument to ShortMessage
's
setMessage(int)
method, you can express
it as 254 or 0xFE.
- See Also:
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Field Summary
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionabstract Object
clone()
Creates a new object of the same class and with the same contents as this object.int
Obtains the total length of the MIDI message in bytes.byte[]
Obtains the MIDI message data.int
Obtains the status byte for the MIDI message.protected void
setMessage
(byte[] data, int length) Sets the data for the MIDI message.
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Field Details
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data
protected byte[] dataThe MIDI message data. The first byte is the status byte for the message; subsequent bytes up to the length of the message are data bytes for this message.- See Also:
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length
protected int lengthThe number of bytes in the MIDI message, including the status byte and any data bytes.- See Also:
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Constructor Details
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MidiMessage
protected MidiMessage(byte[] data) Constructs a newMidiMessage
. This protected constructor is called by concrete subclasses, which should ensure that the data array specifies a complete, valid MIDI message.- Parameters:
data
- an array of bytes containing the complete message. The message data may be changed using thesetMessage
method.- See Also:
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Method Details
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setMessage
Sets the data for the MIDI message. This protected method is called by concrete subclasses, which should ensure that the data array specifies a complete, valid MIDI message.- Parameters:
data
- the data bytes in the MIDI messagelength
- the number of bytes in the data byte array- Throws:
InvalidMidiDataException
- if the parameter values do not specify a valid MIDI meta message
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getMessage
public byte[] getMessage()Obtains the MIDI message data. The first byte of the returned byte array is the status byte of the message. Any subsequent bytes up to the length of the message are data bytes. The byte array may have a length which is greater than that of the actual message; the total length of the message in bytes is reported by thegetLength()
method.- Returns:
- the byte array containing the complete
MidiMessage
data
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getStatus
public int getStatus()Obtains the status byte for the MIDI message. The status "byte" is represented as an integer; see the discussion in theMidiMessage
class description.- Returns:
- the integer representation of this event's status byte
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getLength
public int getLength()Obtains the total length of the MIDI message in bytes. A MIDI message consists of one status byte and zero or more data bytes. The return value ranges from 1 for system real-time messages, to 2 or 3 for channel messages, to any value for meta and system exclusive messages.- Returns:
- the length of the message in bytes
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clone
Creates a new object of the same class and with the same contents as this object.
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