| << Chapter < Page | Chapter >> Page > |
The instance variable named melody will ultimately refer to an array object that holds the audio data that will be played or filed.
The instance variable named args will ultimately refer to an array object that holds an incoming command-line parameter.
Only one command-line parameter is needed and it is optional. If the value of the parameter is "play", the sound will be played immediately. Otherwise, theparameter string will be used as a filename for an audio file of type AU. In this case,it must be a string that would be valid as a file name for your operating system.
The main method simply instantiates a new object of this class passing the incoming args array's reference to the constructor.
I typically use Windows batch files to compile and execute my Java program. Listing 2 shows the contents of such a batch file. This batch file will attempt to:
| Listing 2 . The file named WhiteNoise.bat. |
|---|
echo off
del *.classdel WhiteNoise.au
echo onjavac MusicComposer04.java
java MusicComposer04 playjava MusicComposer04 WhiteNoise
echo offdel *.class
pause |
Listing 3 shows the beginning of the constructor for MusicComposer04 .
| Listing 3 . Beginning of the constructor for MusicComposer04. |
|---|
public MusicComposer04(String[] args){//constructorthis.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 |
The constructor begins by saving the incoming reference to the args array containing the command-line parameter.
If the length of the args array is zero, this means that the user did not enter a command-line parameter. In that case, the constructor instantiates an appropriate arrayobject, populates its only element with a reference to a "play" string, and saves that array object's reference in the instance variable discussed earlier .
Listing 4 instantiates a new object of the WhiteNoise class and saves the object's reference in a local reference variable of type WhiteNoise named whiteNoise . You are already familiar with the three parameters that are passed to the constructor for the WhiteNoise class.
(Later when we discuss runtime polymorphism, we will save such an object's reference in a reference variable of type AudioSignalGenerator02 , which is the immediate superclass of the WhiteNoise class.)
| Listing 4 . Get and play or file the sound. |
|---|
//Get a populated array containing audio data for white or pink noise.
WhiteNoise whiteNoise = new WhiteNoise(audioParams,this.args,melody);melody = whiteNoise.getMelody();
//Play or file the audio datanew AudioPlayOrFile01(audioParams,melody,this.args[0]).playOrFileData();}//end constructor
//-------------------------------------------------------------------------//}//end class MusicComposer04.java |
Notification Switch
Would you like to follow the 'Accessible objected-oriented programming concepts for blind students using java' conversation and receive update notifications?
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|