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Music Theory for Java

Java implementation of Western music theory.

This library implements the widely used concepts in the Western music theory like pitches, pitch classes, intervals, keys, scales, chords etc. in a type-safe manner, using immutable value objects wherever possible.

Adding as Dependency

The library is now hosted at Maven Central https://mvnrepository.com/artifact/io.github.singond/music/. Previously, it was hosted on JCenter, before the service was shut down. The existing releases are apparently still available, but new versions will only be published to Maven Central.

Maven

In pom.xml:

<dependency>
  <groupId>io.github.singond</groupId>
  <artifactId>music</artifactId>
  <version>0.8.0</version>
</dependency>

Gradle

In build.gradle:

repositories {
	mavenCentral()
}
dependencies {
	implementation 'io.github.singond:music:0.8.0'
}

Usage

Basics

The core types implementing music concepts are the following:

Pitch: The pitch of a musical note, consisting of a pitch class and an octave number, like “C4” (C in the fourth octave) or “F#5” (F sharp in the fifth octave).
PitchClass: The group of all pitches an octave apart, like “C” or “Ab” (A flat). This is like Pitch with octave information erased.
Interval: An interval between two pitches, like “minor third”.
Key: A musical key, like “E major” or “F sharp minor”.
KeyType: A type of a musical key, like “major” or “minor”.
Chord: A group of pitch classes, like “major triad at A” (A, C#, E).
ChordVoicing: A group of pitches, like “major triad at A4” (A4, C#5, E5).
ChordType: A type of a chord, like “major triad” or “diminished seventh”.

There are also some utility classes for manipulating the objects:

Pitches: for manipulating instances of Pitch and PitchClass,
Intervals: for manipulating instances of Interval,
Keys: for working with instances of Key.

Examples

For brevity, the following examples don't show the System.out.println(var).

Create pitch from pitch class and octave:

Pitch p = Pitch.of(PitchClass.D, 4);
>> D4

Equality and enharmonicity:

Pitch dSharp = Pitch.DS4;
Pitch eFlat = Pitch.EB4;
boolean equal = dSharp.equals(eFlat);
>> false
boolean enharm = dSharp.isEnharmonicWith(eFlat);
>> true

Get the major third above A4:

Pitch p = Pitch.A4.transposeUp(SimpleInterval.MAJOR_THIRD);
>> C#5

Get the pitch classes in the key of A major and get the second raised degree:

Key key = Keys.A_MAJOR;
>> A major

List<PitchClass> scale = key.degrees();
>> [A, B, C#, D, E, F#, G#]

PitchClass tonic = key.tonic();
>> A

PitchClass secondRaised = key.degree(Degree.II_RAISED);
>> B#

Generate the E major scale between A3 and D5:

Set<PitchClass> pcs = Keys.E_MAJOR.pitchClasses();
List<Pitch> range = Pitches.allBetween(Pitch.A3, Pitch.D5, pcs);
>> [A3, B3, C#4, D#4, E4, F#4, G#4, A4, B4, C#5]

Get the major triad with Eb as root:

Chord c = Chords.chordAtRoot(PitchClass.E_FLAT, Chords.MAJOR_TRIAD);
>> [Eb, G, Bb]

Get the first inversion of a major triad with Eb as root:

// Root position:
PitchClass root = PitchClass.E_FLAT;
ChordType type = Chords.MAJOR_TRIAD;
Chord chord = Chords.chordAtRoot(root, type);
>> [Eb, G, Bb]

// First inversion:
chord = chord.invert(1);
>> [G, Bb, Eb]

// Alternatively, invert the chord type:
type = type.invert(1);
chord = Chords.chordAtRoot(root, type);
>> [G, Bb, Eb]

Get the second inversion of a major triad which has Bb in bass:

PitchClass bass = PitchClass.B_FLAT;
ChordType type = Chords.MAJOR_TRIAD.invert(2);
Chord chord = Chords.chordAtBass(bass, type);
>> [Bb, Eb, G]

Singond / Music