File Handling Classes in Java

File – Managing Files

The java.io.File class is used to represent file and directory pathnames in an abstract manner. It doesn't represent the contents of a file but allows you to create, delete, check properties (like size, existence), and manipulate files or directories

Method	Purpose
createNewFile()	Create file
exists()	Check file exists
getName()	Get file name
getAbsolutePath()	Get file path
canRead()	Check read permission
canWrite()	Check write permission
canExecute()	Check execute permission
length()	File size
delete()	Delete file
mkdir()	Create directory
mkdirs()	Create multiple directories
list()	List files

FileReader – Reading Characters

Convenience class for reading character files. The constructors of this class assume that the default character encoding and the default byte-buffer size are appropriate. To specify these values yourself, construct an InputStreamReader on a FileInputStream.

Method	Purpose
read()	Read one character
read(char[])	Read multiple characters
read(char[], off, len)	Read with position
ready()	Check readiness
skip(n)	Skip characters
getEncoding()	Get encoding
close()	Close file

FileWriter – Writing Data

• If you are just starting with Java, the easiest way to write text to a file is by using the FileWriter class.
• In the example below, we use FileWriter together with its write() method to create and write some text into a file.

Method	Purpose
write(int)	Write one character
write(char[])	Write character array
write(String)	Write string
write(String, off, len)	Write part of string
append()	Add data at end
flush()	Force write
close()	Close file

BufferedReader – Efficient Reading

• The BufferedReader class in Java helps read text efficiently from files or user input. It stores data in a buffer, making reading faster and smoother instead of reading one character at a time.
• Faster Reading Reads large chunks of data at once, reducing the number of read operations.

Method	Purpose
read()	Read one character
readLine()	Read full line
read(char[], off, len)	Read into array
ready()	Check readiness
skip(n)	Skip characters
mark()	Mark position
reset()	Return to mark
close()	Close stream

BufferedWriter – Efficient Writing

The BufferedWriter class is used to write text to a file, one line or one string at a time. If the file already exists, its contents will be replaced (overwritten).

Method	Purpose
write(int)	Write one character
write(char[])	Write character array
write(String)	Write string
write(String, off, len)	Write part of string
newLine()	Add new line
flush()	Force write
close()	Close stream

PrintWriter – Formatted Writing

Unlike the PrintStream class, if automatic flushing is enabled it will be done only when one of the println, printf, or format methods is invoked, rather than whenever a newline character happens to be output. These methods use the platform's own notion of line separator rather than the newline character

Method	Purpose
print()	Write without new line
println()	Write with new line
printf()	Formatted output
format()	Same as printf
write()	Write raw data
append()	Add data
flush()	Force write
close()	Close writer