Added in API level 1

Summary: Ctors | Methods | Protected Methods | Inherited Methods

FileOutputStream

public class FileOutputStream
extends OutputStream

java.lang.Object
↳	java.io.OutputStream
	↳	java.io.FileOutputStream

Known direct subclasses ParcelFileDescriptor.AutoCloseOutputStream ParcelFileDescriptor.AutoCloseOutputStream An OutputStream you can create on a ParcelFileDescriptor, which will take care of calling ParcelFileDescriptor.close() for you when the stream is closed.

Known indirect subclasses AssetFileDescriptor.AutoCloseOutputStream AssetFileDescriptor.AutoCloseOutputStream An OutputStream you can create on a ParcelFileDescriptor, which will take care of calling ParcelFileDescriptor.close() for you when the stream is closed.

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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)

Summary

Public constructors
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.
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.

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 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. static OutputStream nullOutputStream() Returns a new OutputStream which discards all bytes. 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) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
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

FileOutputStream

Added in API level 1

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	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)

FileOutputStream

Added in API level 1

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	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:

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

FileOutputStream

Added in API level 1

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	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:

• SecurityManager.checkWrite(java.io.FileDescriptor)

FileOutputStream

Added in API level 1

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.

Implementation Requirements:

• Invoking this constructor with the parameter name is equivalent to invoking new FileOutputStream(name, false).

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:

• SecurityManager.checkWrite(java.lang.String)

FileOutputStream

Added in API level 1

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	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:

• SecurityManager.checkWrite(java.lang.String)

Public methods

close

Added in API level 1

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.

API Note:

• Overriding close() to perform cleanup actions is reliable only when called directly or when called by try-with-resources. Do not depend on finalization to invoke close; finalization is not reliable and is deprecated. If cleanup of native resources is needed, other mechanisms such as Cleaner should be used.

Throws
IOException	if an I/O error occurs.

getChannel

Added in API level 1

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
FileChannel	the file channel associated with this file output stream

getFD

Added in API level 1

public final 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:

• FileDescriptor

write

Added in API level 1

public 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

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	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

public 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

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()