UML of the File class

The UML of the File class includes:

           _______________________________________
          |              File                     |
	  |_______________________________________|
	  |   - String FileName                   |
	  |_______________________________________|
	  |constructor                            |
	  | + File(String)                        |
	  | + File(String,String)                 |
	  |  ....                                 |
	  |                                       |
	  |query                                  |
	  | + canRead() :boolean                  |
          | + canWrite() :boolean                 |
	  | + exists() :boolean                   |
	  | + getAbsolutePath() :String           |
	  | + isFile() :boolean                   |
	  | + isDirectory() :boolean              |
	  | + length() :long  	                  |
	  | ....                                  |
	  |                                       |
	  |mutator				  |
          | + createNewFile() :boolean            |
	  | + delete() :delete                    |
	  | + deleteOnExit() :void                |
	  | + mkdir() :boolean                    |
	  | + setToReadOnly() :void	  	  |
	  | ....                                  |
	  |_______________________________________|

File Class Specifications

Constructor Method

postcondition A new File object is created and, if possible, associated with the file named s AND Filename == s

public File(String s1,String s2)

postcondition A new File object is created and, if possible, associated with the file named s2 AND Filename == s2 with the location of the file in s1, either a complete path name or a relative name. s1 is said to be the parent of s2.

Query Methods

public boolean canRead()

output

result == true if and only if the file exists and it is permissible for the program to read from the file.

public boolean canWrite()

output

result == true if and only if the file exists and it is permissible for the program to write to this file.

public boolean exists()

output

result == true if and only if the file or directory identified by FileName already exists.

public String getAbsolutePath()

output

result == the complete name associated with FileName (even if the file does not exist)

public boolean isFile()

output

result == true if and only if a file identified by FileName already exists.

public boolean isDirectory()

output

result == true if and only if a directory identified by FileName already exists.

public long length()

output

if the exists() is true, result == the number of bytes occupied by the file/directory

AND if exists() is false, result == 0.

Mutator Methods

public boolean createNewFile()

postcondition

A new, empty file called FileName was created. (Note that any existing file with the same name in the same directory was lost, i.e., clobbered.)

output

result == the file creation was properly performed

public boolean delete()

precondition

exists() is true

postcondition

The file identified by FileName has been deleted from the system.

Output

result == the deletion was properly performed

public void deleteOnExit()

precondition

isFile is true

postcondition

At the time that the currently executing program terminates, the file identified by FileName will be deleted from the file system.

public boolean mkdir()

precondition

exists() is false

postcondition

An empty directory identified by FileName has been constructed

output

result == the directory creation was properly performed

public void setToReadOnly()

precondition

isFile() is true

postcondition

The file identified by FileName has permission that prohibit writing new values into the file.