Class FileOutputStream
- All Implemented Interfaces:
Closeable
,Flushable
,AutoCloseable
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
.
- API Note:
- The
close()
method should be called to release resources used by this stream, either directly, or with thetry
-with-resources statement. - Implementation Requirements:
- Subclasses are responsible for the cleanup of resources acquired by the subclass.
Subclasses requiring that resource cleanup take place after a stream becomes
unreachable should use
Cleaner
or some other mechanism. - Since:
- 1.0
- See Also:
-
Constructor Summary
ConstructorDescriptionFileOutputStream
(File file) Creates a file output stream to write to the file represented by the specifiedFile
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
(File file, boolean append) Creates a file output stream to write to the file represented by the specifiedFile
object.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. -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Closes this file output stream and releases any system resources associated with this stream.Returns the uniqueFileChannel
object associated with this file output stream.final FileDescriptor
getFD()
Returns the file descriptor associated with this stream.void
write
(byte[] b) Writesb.length
bytes from the specified byte array to this file output stream.void
write
(byte[] b, int off, int len) Writeslen
bytes from the specified byte array starting at offsetoff
to this file output stream.void
write
(int b) Writes the specified byte to this file output stream.Methods declared in class java.io.OutputStream
flush, nullOutputStream
-
Constructor Details
-
FileOutputStream
Creates a file output stream to write to the file with the specified name. If the file exists, it is truncated, otherwise a new file is created. Symbolic links are automatically redirected to the target of the link. A newFileDescriptor
object is created to represent this file connection.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 invokingnew FileOutputStream(name, false)
. - 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
-
FileOutputStream
Creates a file output stream to write to the file with the specified name. If the file exists, it is truncated unless the second argument istrue
, in which case bytes will be written to the end of the file rather than the beginning. If the file does not exist, it is created. Symbolic links are automatically redirected to the target of the link. A newFileDescriptor
object is created to represent this file connection.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 nameappend
- iftrue
, 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.- Since:
- 1.1
-
FileOutputStream
Creates a file output stream to write to the file represented by the specifiedFile
object. If the file exists, it is truncated, otherwise a new file is created. Symbolic links are automatically redirected to the target of the link. A newFileDescriptor
object is created to represent this file connection.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- See Also:
-
FileOutputStream
Creates a file output stream to write to the file represented by the specifiedFile
object. If the file exists, it is truncated unless the second argument istrue
, in which case bytes will be written to the end of the file rather than the beginning. If the file does not exist, it is created. Symbolic links are automatically redirected to the target of the link. A newFileDescriptor
object is created to represent this file connection.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
- iftrue
, 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- Since:
- 1.4
- See Also:
-
FileOutputStream
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.If
fdObj
is null then aNullPointerException
is thrown.This constructor does not throw an exception if
fdObj
isinvalid
. However, if the methods are invoked on the resulting stream to attempt I/O on the stream, anIOException
is thrown.- Parameters:
fdObj
- the file descriptor to be opened for writing
-
-
Method Details
-
write
Writes the specified byte to this file output stream. Implements thewrite
method ofOutputStream
.- Specified by:
write
in classOutputStream
- Parameters:
b
- the byte to be written.- Throws:
IOException
- if an I/O error occurs.
-
write
Writesb.length
bytes from the specified byte array to this file output stream.- Overrides:
write
in classOutputStream
- Parameters:
b
- the data.- Throws:
IOException
- if an I/O error occurs.- See Also:
-
write
Writeslen
bytes from the specified byte array starting at offsetoff
to this file output stream.- Overrides:
write
in classOutputStream
- 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.IndexOutOfBoundsException
- Ifoff
is negative,len
is negative, orlen
is greater thanb.length - off
-
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.
- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classOutputStream
- API Note:
- Overriding
close()
to perform cleanup actions is reliable only when called directly or when called by try-with-resources. - Implementation Requirements:
- Subclasses requiring that resource cleanup take place after a stream becomes
unreachable should use the
Cleaner
mechanism.If this stream has an associated channel then this method will close the channel, which in turn will close this stream. Subclasses that override this method should be prepared to handle possible reentrant invocation.
- Throws:
IOException
- if an I/O error occurs.
-
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 thisFileOutputStream
object. - Throws:
IOException
- if an I/O error occurs.- See Also:
-
getChannel
Returns the uniqueFileChannel
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
- Since:
- 1.4
-