Chapter 4, Problem 1E

Explanation of Solution

Given: The project name music-organizer-v1 and the class name MusicOrganizer.

To find: The way to store the names of some audio files and the number of files returned by the numberOfFiles.

Solution:

Open BlueJ and then open a new project named Music-organizer-v1.

To make the instance of the class MusicOrganizer:

Right-click on the class MusicOrganizer.

Select construct new MusicOrganizer() of the class MusicOrganizer to make its instance.

A window would show up which will ask for the name of the instance.

So, enter the name of the instance as objMusicOrg1 in place of default instance name and click on OK button.

After that, right-click on that instance residing on the object bench and then click on the method addFile to add some file names to the instance.

A window would show up asking for the name of the file to add it to the collection.

Enter any file name (along with its location) within the text box linked with it and then click on the OK button.

Repeat this procedure two times to add two file names to the collection.

To examine the number of files stored, right-click on the instance objMusicOrg1 of the class MusicOrganizer and then click on the method getNumberOfFiles.

As we have added two files to the collection, the method result of getNumberOfFiles returned 2.

To print the files stored in the collection of the class instance objMusicOrg1, we require to method call listFile.

When the method listFile is called, a window would show up which will ask for the file index. Since we have stored 2 files in the collection and the indexing in any collection starts form 0, starting from 0 the index will end at 1, that is, from 0 to 1.

Here, 0 shows the first file index and 1 shows the second file index.

Output:

After clicking on the OK button in the window shown above, we get the following result.

Modifying the index at the time of calling the method listFile, we get the filenames stored in that index on the Terminal Window.