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MidiMessage.javaAPI DocJava SE 5 API5768Fri Aug 26 14:57:48 BST 2005javax.sound.midi

MidiMessage

public abstract class MidiMessage extends Object implements Cloneable
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 JavaTM uses signed bytes, the Java Sound API uses integers instead of bytes when expressing MIDI data. For example, the {@link #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 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 hexidecimal notation. For instance, to pass the "active sensing" status byte as the first argument to ShortMessage's {@link ShortMessage#setMessage(int) setMessage(int)} method, you can express it as 254 or 0xFE.

see
Track
see
Sequence
see
Receiver
version
1.29, 03/12/19
author
David Rivas
author
Kara Kytle

Fields Summary
protected byte[]
data
The 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.
protected int
length
The number of bytes in the MIDI message, including the status byte and any data bytes.
Constructors Summary
protected MidiMessage(byte[] data)
Constructs a new MidiMessage. This protected constructor is called by concrete subclasses, which should ensure that the data array specifies a complete, valid MIDI message.

param
data an array of bytes containing the complete message. The message data may be changed using the setMessage method.
see
#setMessage



                                                         
       
	this.data = data;
	if (data != null) {
	    this.length = data.length;
	}
Methods Summary
public abstract java.lang.Objectclone()
Creates a new object of the same class and with the same contents as this object.

return
a clone of this instance.

public intgetLength()
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.
return
the length of the message in bytes
	return length;
    
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 the {@link #getLength}
method.
return
the byte array containing the complete MidiMessage data
	byte[] returnedArray = new byte[length];
	System.arraycopy(data, 0, returnedArray, 0, length);
	return returnedArray;
    
public intgetStatus()
Obtains the status byte for the MIDI message. The status "byte" is
represented as an integer; see the
discussion in the
MidiMessage class description.
return
the integer representation of this event's status byte
	if (length > 0) {
	    return (data[0] & 0xFF);
	}
	return 0;
    
protected voidsetMessage(byte[] data, int length)
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.
	if (length < 0 || (length > 0 && length > data.length)) {
	    throw new IndexOutOfBoundsException("length out of bounds: "+length);
	}
	this.length = length;

	if (this.data == null || this.data.length < this.length) {
	    this.data = new byte[this.length];
	}
	System.arraycopy(data, 0, this.data, 0, length);