Recursive Structures Lab

Introduction

The goal of this lab is to practice using recursion to interact with recursively structured data. One example of a recursively structured collection is the file system of a computer. A file system is made up of directories, each of which may contain additional directories, and so forth.

Please watch this 6-minute video by Gayle Laakmann McDowell :

Source Files

The following files are provided:

1. DirectorySearcher.java – This (unfinished) class is responsible for recursively traversing a directory tree starting from a designated directory.
2. DirectoryDriver.java – This is a driver class for executing the methods provided by DirectorySearcher. As currently written, the main method uses a DirectorySearcher to list the contents of the current directory.

Instructions

1. Download and test the two files above. Make sure you understand how the existing code works.
   • if you run it as it is when you first download it, you should see something like:

     bin	(Directory)
     .classpath
     .settings	(Directory)
     .project
     src	(Directory)
     

2. Complete the listDirectories (plural) method of the DirectorySearcher class. Test your method by modifying the driver so that it calls this method instead of listDirectory (singular).
   • Your solution should print a "/" after each directory name and indent the files under each directory. For example,
     1. if the starting path is ".", the output might look like this:

        ./
            bin/
                DirectorySearcher.class
                DirectoryDriver.class
            .classpath
            .settings/
                org.eclipse.core.resources.prefs
            .project
            src/
                DirectorySearcher.java
                DirectoryDriver.java
        

     2. if the starting path is "../PA4", the output might look like this:

        PA4/
            bin/
                GameUtils.class
                AsteroidsGame.class
                Bullet.class
                Pose.class
                Asteroid.class
                Enemy.class
                Vector2D.class
                Ship.class
                AsteroidSize.class
                Playable.class
                Point.class
                Saucer.class
                Drawable.class
                Updatable.class
                GameElement.class
                StdDraw$RetinaImageIcon.class
                GameDriver.class
                StdDraw.class
                Star.class
                NumericDisplay.class
            .classpath
            .settings/
                org.eclipse.core.resources.prefs
            .project
            src/
                Playable.java
                Drawable.java
                Saucer.java
                Star.java
                Enemy.java
                Point.java
                AsteroidSize.java
                Ship.java
                GameElement.java
                GameUtils.java
                AsteroidsGame.java
                Bullet.java
                GameDriver.java
                NumericDisplay.java
                Pose.java
                Asteroid.java
                Vector2D.java
                StdDraw.java
                Updatable.java
        

3. Complete the searchDirectories method of the DirectorySearcher class. Test your method by modifying the driver; search for different patterns to make sure it works.
   • Your solution should print the path to each file that is found. (Just print the File object itself, rather than calling getName.) For example, if the search string is "se", the output might look like this:

     ../PA4/bin/Pose.class
     ../PA4/.settings
     ../PA4/.settings/org.eclipse.core.resources.prefs
     ../PA4/src/Pose.java
     

   • while if you searched for empty string "", the output might be:

     ../PA4
     ../PA4/.DS_Store
     ../PA4/bin
     ../PA4/bin/GameUtils.class
     ../PA4/bin/AsteroidsGame.class
     ../PA4/bin/Bullet.class
     ../PA4/bin/Pose.class
     ../PA4/bin/Asteroid.class
     ../PA4/bin/Enemy.class
     ../PA4/bin/Vector2D.class
     ../PA4/bin/Ship.class
     ../PA4/bin/AsteroidSize.class
     ../PA4/bin/Playable.class
     ../PA4/bin/Point.class
     ../PA4/bin/Saucer.class
     ../PA4/bin/Drawable.class
     ../PA4/bin/Updatable.class
     ../PA4/bin/GameElement.class
     ../PA4/bin/StdDraw$RetinaImageIcon.class
     ../PA4/bin/GameDriver.class
     ../PA4/bin/StdDraw.class
     ../PA4/bin/Star.class
     ../PA4/bin/NumericDisplay.class
     ../PA4/.classpath
     ../PA4/.settings
     ../PA4/.settings/org.eclipse.core.resources.prefs
     ../PA4/.project
     ../PA4/src
     ../PA4/src/Playable.java
     ../PA4/src/Drawable.java
     ../PA4/src/Saucer.java
     ../PA4/src/Star.java
     ../PA4/src/Enemy.java
     ../PA4/src/Point.java
     ../PA4/src/AsteroidSize.java
     ../PA4/src/Ship.java
     ../PA4/src/GameElement.java
     ../PA4/src/GameUtils.java
     ../PA4/src/AsteroidsGame.java
     ../PA4/src/Bullet.java
     ../PA4/src/GameDriver.java
     ../PA4/src/NumericDisplay.java
     ../PA4/src/Pose.java
     ../PA4/src/Asteroid.java
     ../PA4/src/Vector2D.java
     ../PA4/src/StdDraw.java
     ../PA4/src/Updatable.java
     

4. Submit your completed DirectorySearcher.java file via GradeScope.