FileWriter

AI-generated Key Takeaways

• FileWriter is a convenience class in Java for writing character streams to files, using default encoding and buffer size.

• It provides constructors that accept file names, File objects, or file descriptors, with options for appending data.

• FileWriter relies on the underlying platform for file availability and may fail if a file is already open for writing by another process.

• For writing raw byte streams, FileOutputStream is recommended instead of FileWriter.

public class FileWriter extends OutputStreamWriter

Convenience class for writing character files. The constructors of this class assume that the default character encoding and the default byte-buffer size are acceptable. To specify these values yourself, construct an OutputStreamWriter on a FileOutputStream.

Whether or not a file is available or may be created depends upon the underlying platform. Some platforms, in particular, allow a file to be opened for writing by only one FileWriter (or other file-writing object) at a time. In such situations the constructors in this class will fail if the file involved is already open.

FileWriter is meant for writing streams of characters. For writing streams of raw bytes, consider using a FileOutputStream.

See Also

• OutputStreamWriter
• FileOutputStream

Inherited Field Summary

From class java.io.Writer

protected Object

lock

The object used to synchronize operations on this stream.

Public Constructor Summary

	FileWriter(String fileName) Constructs a FileWriter object given a file name.
	FileWriter(String fileName, boolean append) Constructs a FileWriter object given a file name with a boolean indicating whether or not to append the data written.
	FileWriter(File file) Constructs a FileWriter object given a File object.
	FileWriter(File file, boolean append) Constructs a FileWriter object given a File object.
	FileWriter(FileDescriptor fd) Constructs a FileWriter object associated with a file descriptor.

Inherited Method Summary

From class java.io.OutputStreamWriter

void	close() Closes this writer.
void	flush() Flushes this writer.
String	getEncoding() Returns the canonical name of the encoding used by this writer to convert characters to bytes, or null if this writer has been closed.
void	write(int oneChar) Writes the character oneChar to this writer.
void	write(String str, int offset, int count) Writes count characters starting at offset in str to this writer.
void	write(char[] buffer, int offset, int count) Writes count characters starting at offset in buf to this writer.

From class java.io.Writer

Writer	append(char c) Appends the specified character to this writer.
Writer	append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this writer.
Writer	append(CharSequence csq) Appends the specified character sequence to this writer.
abstract void	close() Closes the stream, flushing it first.
abstract void	flush() Flushes the stream.
void	write(String str) Writes a string.
void	write(int c) Writes a single character.
void	write(String str, int off, int len) Writes a portion of a string.
abstract void	write(char[] cbuf, int off, int len) Writes a portion of an array of characters.
void	write(char[] cbuf) Writes an array of characters.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.lang.Appendable

abstract Appendable	append(char c) Appends the specified character to this Appendable.
abstract Appendable	append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this Appendable.
abstract Appendable	append(CharSequence csq) Appends the specified character sequence to this Appendable.

From interface java.io.Closeable

abstract void

close() Closes this stream and releases any system resources associated with it.

From interface java.io.Flushable

abstract void

flush() Flushes this stream by writing any buffered output to the underlying stream.

From interface java.lang.AutoCloseable

abstract void

close() Closes this resource, relinquishing any underlying resources.

Public Constructors

public FileWriter (String fileName)

Constructs a FileWriter object given a file name.

Parameters

fileName	String The system-dependent filename.

Throws

IOException	if the named file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason

public FileWriter (String fileName, boolean append)

Constructs a FileWriter object given a file name with a boolean indicating whether or not to append the data written.

Parameters

fileName	String The system-dependent filename.
append	boolean if true, then data will be written to the end of the file rather than the beginning.

Throws

IOException	if the named file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason

public FileWriter (File file)

Constructs a FileWriter object given a File object.

Parameters

file	a File object to write to.

Throws

IOException	if the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason

public FileWriter (File file, boolean append)

Constructs a FileWriter object given a File object. If the second argument is true, then bytes will be written to the end of the file rather than the beginning.

Parameters

file	a File object to write to
append	if true, then bytes will be written to the end of the file rather than the beginning

Throws

IOException	if the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason

public FileWriter (FileDescriptor fd)

Constructs a FileWriter object associated with a file descriptor.

Parameters

fd	FileDescriptor object to write to.