Java Reference
In-Depth Information
We now present the most important classes for reading and writing ASCII text files
and some of their methods.
10.1.1
The class
File
The class
File
is the Java abstraction of a file or directory on the hard disk or
some other storage medium; we shall use the term 'hard disk' in the following.
Below we list a constructor and some methods we need:
File(String filename)
boolean
exists()
boolean
delete();
boolean
renameTo(File newName)
boolean
createNewFile()
boolean
isDirectory()
String getName()
String getPath()
!
File(String filename)
creates a file object for a file with name
filename
. Note
that neither an existing file with that name is opened nor is a file created on
the hard disk.
exists()
returns true if the file exists.
delete()
deletes the file from the hard disk and returns
true
if successful or
false
otherwise, e.g. if the file did not exist.
renameTo(File newName)
renames the file. The new name is that of the file object
newName
.
createNewFile()
creates a file on the hard disk. The file name is that specified
in the constructor, but only if the file does not already exist. If successful it
returns
true
and
false
otherwise.
isDirectory()
returns
true
if the file is a directory and
false
otherwise.
getName()
returns just the file name, without the path but with extension.
getPath()
returns the whole path including file name and extension.
Possible file names (the last one is directory) are, for example
testFile.txt
C:/Java/kurs/FileIO/scr/testFile.txt
C:
\\
Java
\\
kurs
\\
FileIO
\\
scr
\\
testFile.txt
∼
/Java/kurs/FileIO/testFile.txt
./FileIO/testFile.txt
C:/Java/
!
Note that under MS Windows one can use both
/
or
\
as a separator. Because of
the special meaning of backslash in Java strings it has to be duplicated.
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