Class FileOutputStream
- java.lang.Object
-
- java.io.OutputStream
-
- java.io.FileOutputStream
- All Implemented Interfaces:
-
Closeable
,Flushable
,AutoCloseable
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
.
- API Note:
- To release resources used by this stream
close()
should be called directly or by try-with-resources. Subclasses are responsible for the cleanup of resources acquired by the subclass. Subclasses that overridefinalize()
in order to perform cleanup should be modified to use alternative cleanup mechanisms such asCleaner
and remove the overridingfinalize
method. - Implementation Requirements:
- If this FileOutputStream has been subclassed and the
close()
method has been overridden, theclose()
method will be called when the FileInputStream is unreachable. Otherwise, it is implementation specific how the resource cleanup described inclose()
is performed. - Since:
- 1.0
- See Also:
-
File
,FileDescriptor
,FileInputStream
,Files.newOutputStream(java.nio.file.Path, java.nio.file.OpenOption...)
Constructor Summary
Constructor | Description |
---|---|
FileOutputStream(File file) | Creates a file output stream to write to the file represented by the specified |
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 specified |
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 Type | Method | Description |
---|---|---|
void | close() | Closes this file output stream and releases any system resources associated with this stream. |
protected void | finalize() | Deprecated, for removal: This API element is subject to removal in a future version. The finalize method has been deprecated and will be removed. |
FileChannel | getChannel() | Returns the unique |
FileDescriptor | getFD() | Returns the file descriptor associated with this stream. |
void | write(byte[] b) | Writes |
void | write(byte[] b,
int off,
int len) | Writes |
void | write(int b) | Writes the specified byte to this file output stream. |
Methods declared in class java.io.OutputStream
flush, nullOutputStream
Methods declared in class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
FileOutputStream
public FileOutputStream(String name) throws FileNotFoundException
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 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 -
SecurityException
- if a security manager exists and itscheckWrite
method denies write access to the file. - See Also:
SecurityManager.checkWrite(java.lang.String)
FileOutputStream
public FileOutputStream(String name, boolean append) throws FileNotFoundException
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
- 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. -
SecurityException
- if a security manager exists and itscheckWrite
method denies write access to the file. - Since:
- 1.1
- See Also:
SecurityManager.checkWrite(java.lang.String)
FileOutputStream
public FileOutputStream(File file) throws FileNotFoundException
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 itscheckWrite
method denies write access to the file. - See Also:
-
File.getPath()
,SecurityException
,SecurityManager.checkWrite(java.lang.String)
FileOutputStream
public FileOutputStream(File file, boolean append) throws FileNotFoundException
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
- 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 -
SecurityException
- if a security manager exists and itscheckWrite
method denies write access to the file. - Since:
- 1.4
- See Also:
-
File.getPath()
,SecurityException
,SecurityManager.checkWrite(java.lang.String)
FileOutputStream
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 - Throws:
-
SecurityException
- if a security manager exists and itscheckWrite
method denies write access to the file descriptor - See Also:
SecurityManager.checkWrite(java.io.FileDescriptor)
Method Detail
write
public void write(int b) throws IOException
Writes the specified byte to this file output stream. Implements the write
method of OutputStream
.
- Specified by:
-
write
in classOutputStream
- Parameters:
-
b
- the byte to be written. - Throws:
-
IOException
- if an I/O error occurs.
write
public void write(byte[] b) throws IOException
Writes b.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:
OutputStream.write(byte[], int, int)
write
public void write(byte[] b, int off, int len) throws IOException
Writes len
bytes from the specified byte array starting at offset off
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.
close
public void close() throws IOException
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. Do not depend on finalization to invokeclose
; 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.
getFD
public final FileDescriptor getFD() throws IOException
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:
FileDescriptor
getChannel
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
- Since:
- 1.4
finalize
@Deprecated(since="9", forRemoval=true) protected void finalize() throws IOException
finalize
method has been deprecated and will be removed. Subclasses that override finalize
in order to perform cleanup should be modified to use alternative cleanup mechanisms and to remove the overriding finalize
method. When overriding the finalize
method, its implementation must explicitly ensure that super.finalize()
is invoked as described in Object.finalize()
. See the specification for Object.finalize()
for further information about migration options.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. The finalize()
method does not call close()
directly.
- Overrides:
-
finalize
in classObject
- API Note:
- To release resources used by this stream
close()
should be called directly or by try-with-resources. - Implementation Requirements:
- If this FileOutputStream has been subclassed and the
close()
method has been overridden, theclose()
method will be called when the FileOutputStream is unreachable. Otherwise, it is implementation specific how the resource cleanup described inclose()
is performed. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FileInputStream.close()