The document discusses the Java File class, which represents file paths and allows file system operations without reading or writing files. It describes important File class methods for querying and modifying files and directories. It also covers the different types of paths like relative, absolute, and canonical, and how methods like getPath(), getAbsolutePath(), and getCanonicalPath() resolve the paths. Finally, it mentions the platform-specific file separator character used in file paths.

1. Java File class
Sujit Kumar
Zenolocity LLC
Copyright @ 2012 - 2024

2. File Paths
• java.io.File class for representing and
manipulating file paths and do file system
operations.
• File object is immutable. Cannot modify what
it represents after it is created.
• Important: File class is NOT used to read from
a file or write to a file on disk.
• File object can be created with an absolute or
a relative path name.

3. Important Methods in File Class
• File System Query methods:
canRead(), canWrite(), exists(), isDirectory(),
isFile(), isHidden(), getAbsolutePath(),
lastModified(), length(), listFiles(), listRoots()
• File System Modification methods:
createNewFile(), mkdir(), renameTo(), delete(),
deleteOnExit(), setReadOnly(), setLastModified()

4. Types of Paths
• Relative, Absolute and Canonical
• getPath(), getAbsolutePath() and getCanonicalPath()
• getPath() is the path that the File object was
constructed with & it may or may not be a relative
path.
• getAbsolutePath() gets the path string after resolving it
against the current directory if it's relative, resulting in
a fully qualified path.
• getCanonicalPath() gets the path string after resolving
any relative path against current directory and removes
any relative paths (. and ..), and any file system
symbolic links to return an absolute path.

5. Types of Paths (contd…)
• getAbsolutePath() gives you an absolute path
to the file
• getCanonicalPath() gives you the unique
absolute path to the file. Note that there are
more than one absolute paths that point to
the same file, but only one canonical path.

6. File Separator
• Platform specific directory separator delimiter.
• System property called "file.separator“.
• This character separates components of a file
path. This is "/" on UNIX and "" on Windows.
Examples:
/usr/home/kumar/foo.txt on Unix
C:usrhomekumarfoo.txt on Windows