FileSystem

This is a basic File System created using Java Object Oriented Principles.
I have provided the functions to create, move, delete entities and write to a text file.

######User can,

1. create, move, delete any entity.
   
2. write string to a Text File.
   
   

######User cannot,

1. move or delete any entities in/from a zipFile.
   
2. set/update size of an entity.
   
   

######FILESYSTEM STRUCTURE:

1. File System has set of Drives with the default C drive.
   
2. Each Drive, Folder and ZipFiles can contain Folders, ZipFiles and TextFiles.
   
   

######CLASSES:

1. Abstract Class FileSystem.
   
2. Abstract Class Entity that extends to FileSystem.
   
3. Classes Drive, Folder, ZipFile and TextFile extends Entity.
   
4. Classes for Custom Exceptions.
   
   

######THINGS TO NOTE:

1. FileSystem creates a default C drive to serve the user well.
   
2. To avoid duplicates, every Entity maintains a Set of Entity Names it contains.
   
3. Size gets updated automatically when you write or change the contents of a text file.
   
4. Size of an entity is calculated recursively with the entities they hold.
   
5. Size of a textFile is equal to the size of its contents.
   
6. Size of a Folder, Drive and zipFile is measured with the sum of sizes of its contents
   
7. Size of a zipFile is always half its actual size.