0.9 Jbs2050-runtime polymorphism with java sound

Table of contents

• Preface
  • Viewing tip
    • Listings
• General background information
• Discussion and sample code
  • The class named MusicComposer08
    • Beginning of the class named MusicComposer08
    • Create and populate an array holding references to audio objects
    • Override an inherited abstract method
    • Call the getMelody method on a subclass object selected at random
    • Some new melodies
    • Play or file the melody
    • An extremely important concept
• Run the program
• Miscellaneous
• Complete program listings

Preface

This module is part of a collection titled Accessible Objected-Oriented Programming Concepts for Blind Students using Java . It demonstrates runtime polymorphism using an array of the abstract type AudioSignalGenerator02 populated with references to objects of eight different subclasses of AudioSignalGenerator02 in a format that is accessible to blind students.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find the listings while you are reading about them.

Listings

• Listing 1 . Beginning of the class named MusicComposer08.
• Listing 2 . Create and populate an array holding references to audio objects.
• Listing 3 . Call the getMelody method on a subclass object selected at random.
• Listing 4 . Play or file the melody.
• Listing 5 . The class named AudioGraphSinusoidal.
• Listing 6 . The class named AudioGraphSquareWave.
• Listing 7 . The class named FMSweep.
• Listing 8 . The class named MusicComposer08.
• Listing 9 . The class named SquareWave.
• Listing 10 . The class named StereoPingpong.
• Listing 11 . The class named ToneMono.
• Listing 12 . The class named TonesStereo.
• Listing 13 . The class named WhiteNoise.
• Listing 14 . The class named AudioFormatParameters01.
• Listing 15 . The class named AudioPlayOrFile01.
• Listing 16 . The class named AudioSignalGenerator02.

General background information

We have reached a plateau of sorts in our study of Java sound. This and previous modules have produced hard-coded sounds. Future modules will be moreflexible. For example, one future module will simulate a player piano. It will accept information about a melody as input data at runtime and will tailor the sound based on that information. Forexample, in future modules, you will learn to write a program to produce sounds like Greensleeves and MaryHadALittlelamb .

But I am getting ahead of myself. In previous modules, you have learned:

• A little about the physical characteristics of sound.
• How to produce white or pink noise.
• How to produce square wave sound.
• How to produce a pure sinusoidal tone.
• How to produce an audio graph of a sinusoid.

In this module, you will learn how to produce a few more types of sounds:

• An audio graph for a square wave.
• A frequency-modulated sweep in stereo.
• A stereo ping pong effect.
• A pair of pure tones of different frequencies in stereo.