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:

DirectorySearcher.java – This (unfinished) class is responsible for recursively traversing a directory tree starting from a designated directory.
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

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)
```

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,

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

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

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

Submit your completed DirectorySearcher.java file via GradeScope.