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FileOutputStream

public class FileOutputStream
extends OutputStream

java.lang.Object
   ↳ java.io.OutputStream
     ↳ java.io.FileOutputStream
Known Direct Subclasses
Known Indirect Subclasses


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:

Summary

Public constructors

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 methods

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 methods

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 methods

From class java.io.OutputStream
From class java.lang.Object
From interface java.io.Closeable
From interface java.io.Flushable
From interface java.lang.AutoCloseable

Public constructors

FileOutputStream

Added in API level 1
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 String: 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:

FileOutputStream

Added in API level 1
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 String: the system-dependent file name
append boolean: 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:

FileOutputStream

Added in API level 1
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 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:

FileOutputStream

Added in API level 1
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 File: the file to be opened for writing.
append boolean: 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:

FileOutputStream

Added in API level 1
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 FileDescriptor: the file descriptor to be opened for writing
Throws
SecurityException if a security manager exists and its checkWrite method denies write access to the file descriptor

See also:

Public methods

close

Added in API level 1
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.

getChannel

Added in API level 1
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
FileChannel the file channel associated with this file output stream

getFD

Added in API level 1
FileDescriptor getFD ()

Returns the file descriptor associated with this stream.

Returns
FileDescriptor 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:

write

Added in API level 1
void write (byte[] b)

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

Parameters
b byte: the data.
Throws
IOException if an I/O error occurs.

write

Added in API level 1
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 byte: the data.
off int: the start offset in the data.
len int: the number of bytes to write.
Throws
IOException if an I/O error occurs.

write

Added in API level 1
void write (int b)

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

Parameters
b int: the byte to be written.
Throws
IOException if an I/O error occurs.

Protected methods

finalize

Added in API level 1
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:

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