FileOutputStream

public class FileOutputStream extends OutputStream

A file output stream is an output stream for writing data to a File or to a FileDescriptor. 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 FileOutputStream (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.

FileOutputStream is meant for writing streams of raw bytes such as image data. For writing streams of characters, consider using FileWriter.

See Also

• File
• FileDescriptor
• FileInputStream
• Files.newOutputStream(Path, OpenOption...)

Public Constructor Summary

	FileOutputStream(String name) Creates a file output stream to write to the file with the specified name.
	FileOutputStream(String name, boolean append) Creates a file output stream to write to the file with the specified name.
	FileOutputStream(File file) Creates a file output stream to write to the file represented by the specified File object.
	FileOutputStream(File file, boolean append) Creates a file output stream to write to the file represented by the specified File object.
	FileOutputStream(FileDescriptor fdObj) Creates a file output stream to write to the specified file descriptor, which represents an existing connection to an actual file in the file system.

Public Method Summary

void	close() Closes this file output stream and releases any system resources associated with this stream.
FileChannel	getChannel() Returns the unique FileChannel object associated with this file output stream.
final FileDescriptor	getFD() Returns the file descriptor associated with this stream.
void	write(byte[] b) Writes b.length bytes from the specified byte array to this file output stream.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this file output stream.
void	write(int b) Writes the specified byte to this file output stream.

Protected Method Summary

void	finalize() Cleans up the connection to the file, and ensures that the close method of this file output stream is called when there are no more references to this stream.

Inherited Method Summary

From class java.io.OutputStream

void	close() Closes this output stream and releases any system resources associated with this stream.
void	flush() Flushes this output stream and forces any buffered output bytes to be written out.
void	write(byte[] b) Writes b.length bytes from the specified byte array to this output stream.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this output stream.
abstract void	write(int b) Writes the specified byte to this output stream.

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.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 FileOutputStream (String name)

Creates a file output stream to write to the file with the specified name. A new FileDescriptor object is created to represent this file connection.

First, if there is a security manager, its checkWrite method is called with name as its argument.

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 then a FileNotFoundException is thrown.

Parameters

name	the system-dependent filename

Throws

FileNotFoundException	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
SecurityException	if a security manager exists and its checkWrite method denies write access to the file.

See Also

• SecurityManager.checkWrite(java.lang.String)

public FileOutputStream (String name, boolean append)

Creates a file output stream to write to the file with the specified name. If the second argument is true, then bytes will be written to the end of the file rather than the beginning. A new FileDescriptor object is created to represent this file connection.

First, if there is a security manager, its checkWrite method is called with name as its argument.

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 then a FileNotFoundException is thrown.

Parameters

name	the system-dependent file name
append	if true, then bytes will be written to the end of the file rather than the beginning

Throws

FileNotFoundException	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.
SecurityException	if a security manager exists and its checkWrite method denies write access to the file.

See Also

• SecurityManager.checkWrite(java.lang.String)

public FileOutputStream (File file)

Creates a file output stream to write to the file represented by the specified File object. A new FileDescriptor object is created to represent this file connection.

First, if there is a security manager, its checkWrite method is called with the path represented by the file argument as its argument.

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 then a FileNotFoundException is thrown.

Parameters

file	the file to be opened for writing.

Throws

FileNotFoundException	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
SecurityException	if a security manager exists and its checkWrite method denies write access to the file.

See Also

• File.getPath()
• SecurityException
• SecurityManager.checkWrite(java.lang.String)

public FileOutputStream (File file, boolean append)

Creates a file output stream to write to the file represented by the specified File object. If the second argument is true, then bytes will be written to the end of the file rather than the beginning. A new FileDescriptor object is created to represent this file connection.

First, if there is a security manager, its checkWrite method is called with the path represented by the file argument as its argument.

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 then a FileNotFoundException is thrown.

Parameters

file	the file to be opened for writing.
append	if true, then bytes will be written to the end of the file rather than the beginning

Throws

FileNotFoundException	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
SecurityException	if a security manager exists and its checkWrite method denies write access to the file.

See Also

• File.getPath()
• SecurityException
• SecurityManager.checkWrite(java.lang.String)

public FileOutputStream (FileDescriptor fdObj)

Creates a file output stream to write to the specified file descriptor, which represents an existing connection to an actual file in the file system.

First, if there is a security manager, its checkWrite method is called with the file descriptor fdObj argument as its argument.

If fdObj is null then a NullPointerException is thrown.

This constructor does not throw an exception if fdObj is invalid. However, if the methods are invoked on the resulting stream to attempt I/O on the stream, an IOException is thrown.

Parameters

fdObj	the file descriptor to be opened for writing

Public Methods

public void close ()

Closes this file output stream and releases any system resources associated with this stream. This file output stream may no longer be used for writing bytes.

If this stream has an associated channel then the channel is closed as well.

Throws

IOException	if an I/O error occurs.

public FileChannel getChannel ()

Returns the unique FileChannel object associated with this file output stream.

The initial position of the returned channel will be equal to the number of bytes written to the file so far unless this stream is in append mode, in which case it will be equal to the size of the file. Writing bytes to this stream will increment the channel's position accordingly. Changing the channel's position, either explicitly or by writing, will change this stream's file position.

Returns

• the file channel associated with this file output stream

public final FileDescriptor getFD ()

Returns the file descriptor associated with this stream.

Returns

• the FileDescriptor object that represents the connection to the file in the file system being used by this FileOutputStream object.

Throws

IOException	if an I/O error occurs.

See Also

• FileDescriptor

public void write (byte[] b)

Writes b.length bytes from the specified byte array to this file output stream.

Parameters

b	the data.

Throws

IOException	if an I/O error occurs.

public void write (byte[] b, int off, int len)

Writes len bytes from the specified byte array starting at offset off to this file output stream.

Parameters

b	the data.
off	the start offset in the data.
len	the number of bytes to write.

Throws

IOException	if an I/O error occurs.

public void write (int b)

Writes the specified byte to this file output stream. Implements the write method of OutputStream.

Parameters

b	the byte to be written.

Throws

IOException	if an I/O error occurs.

Protected Methods

protected void finalize ()

Cleans up the connection to the file, and ensures that the close method of this file output stream is called when there are no more references to this stream.

Throws

IOException	if an I/O error occurs.

See Also

• FileInputStream.close()