<< Chapter < Page Chapter >> Page >

More importantly, you will learn how to bring all of this knowledge together to demonstrate runtime polymorphism using sound.

This program requires access to the following classes:

  • AudioGraphSinusoidal
  • AudioGraphSquareWave
  • FMSweep
  • MusicComposer08
  • SquareWave
  • StereoPingpong
  • ToneMono
  • TonesStereo
  • WhiteNoise
  • AudioFormatParameters01
  • AudioPlayOrFile01
  • AudioSignalGenerator02

You will find source code for all of these classes in Listing 5 through Listing 16 .

You are already familiar with some of these classes because they were used in earlier modules.

The driver class for this program is the class named MusicComposer08 . That is the only one of the twelve classes that I will discuss in detail. I willleave it as an exercise for the students at this point to study and understand the remaining eleven classes.

Discussion and sample code

The class named MusicComposer08

The purpose of this program is to demonstrate late binding and runtime polymorphism . This is accomplished by using an array of the abstract type AudioSignalGenerator02 populated with references to objects of the following eight classes :

  • AudioGraphSinusoidal
  • AudioGraphSquareWave
  • FMSweep
  • SquareWave
  • StereoPingpong
  • ToneMono
  • TonesStereo
  • WhiteNoise

Each of the classes listed above extends the abstract class named AudioSignalGenerator02 and overrides the inherited abstract method named getMelody .

After the array is populated, a random number generator is used to get a random index into the array. The getMelody method is called on the reference pointed to by the random index. This causes the sound created by that particular audioobject to be played or filed.

This is an example of late binding and runtime polymorphism because the compiler cannot possibly know the value of the random index when the programis compiled.

As in previous modules, the sound can be played immediately or can be saved in an audio file of type AU for playback later. You should be able to play the audio file with anystandard media player that can handle the AU file type.

The program also requires access to the following classes:

  • AudioFormatParameters01
  • AudioPlayOrFile01
  • AudioSignalGenerator02

Beginning of the class named MusicComposer08

Listing 1 shows the beginning of the class named MusicComposer08 . The code in Listing 1 is essentially the same as code that I have explained in several previous modules. Therefore, no further discussion of the code in Listing 1 will be provided in this module.

Listing 1 . Beginning of the class named MusicComposer08.
import java.util.Random; public class MusicComposer08{//Instantiate an object containing audio format parameters with predefined // values. They may be modified by the signal generator at runtime. Values// allowed by Java SDK 1.4.1 are shown in comments in the class definition. AudioFormatParameters01 audioParams = new AudioFormatParameters01();//A buffer to hold the audio data that will be played or filed.byte[] melody;//A place to store the incoming args array. String[]args; //-------------------------------------------------------------------------////Command-line parameter (only one parameter is needed) //If "play", the sound will be played immediately. Otherwise, the string will// be used as a filename for an audio file of type AU. In the latter case, // it must be a string that would be valid as a file name for the operating// system in use. public static void main(String[]args){ //Instantiate a new object of this class.new MusicComposer08(args); }//end main//-------------------------------------------------------------------------//public MusicComposer08(String[] args){//constructor//Save the args array. this.args = args;//Create default args data if no args data is provided on the command line.if(args.length == 0){ this.args = new String[1]; this.args[0]= "play";//Play the melody immediately }//end if

Questions & Answers

discuss how the following factors such as predation risk, competition and habitat structure influence animal's foraging behavior in essay form
Burnet Reply
location of cervical vertebra
KENNEDY Reply
What are acid
Sheriff Reply
define biology infour way
Happiness Reply
What are types of cell
Nansoh Reply
how can I get this book
Gatyin Reply
what is lump
Chineye Reply
what is cell
Maluak Reply
what is biology
Maluak
what's cornea?
Majak Reply
what are cell
Achol
Explain the following terms . (1) Abiotic factors in an ecosystem
Nomai Reply
Abiotic factors are non living components of ecosystem.These include physical and chemical elements like temperature,light,water,soil,air quality and oxygen etc
Qasim
Define the term Abiotic
Marial
what is biology
daniel Reply
what is diffusion
Emmanuel Reply
passive process of transport of low-molecular weight material according to its concentration gradient
AI-Robot
what is production?
Catherine
hello
Marial
Pathogens and diseases
how did the oxygen help a human being
Achol Reply
how did the nutrition help the plants
Achol Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Accessible objected-oriented programming concepts for blind students using java. OpenStax CNX. Sep 01, 2014 Download for free at https://legacy.cnx.org/content/col11349/1.17
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Accessible objected-oriented programming concepts for blind students using java' conversation and receive update notifications?

Ask