Directory and Filesystem Operations - Java - page 440

Solution

Use a java.io.File object.

Discussion

The File class has a number of “informational” methods. To use any of these, you must con-
struct a File object containing the name of the file it is to operate upon. It should be noted
up front that creating a File object has no effect on the permanent filesystem; it is only an
object in Java's memory. You must call methods on the File object in order to change the
filesystem; as we'll see, there are numerous “change” methods, such as one for creating a
new (but empty) file, one for renaming a file, etc., as well as many informational methods.
Table 11-1 lists some of the informational methods.

Table 11-1. java.io.File methods

Return type Method name Meaning

True if something of that name exists boolean exists()

getCanonicalPath() Full name String

Relative filename

String getName()

Parent directory String getParent()

True if file is readable

boolean canRead()

True if file is writable

boolean canWrite()

File modification time long lastModified()

File size

long length()

True if it's a file

boolean isFile()

True if it's a directory (note: it might be neither)

You can't change the name stored in a File object; you simply create a new File object
each time you need to refer to a different file: