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public class

FileOutputStream

extends OutputStream
implements Closeable
java.lang.Object
   ↳ java.io.OutputStream
     ↳ java.io.FileOutputStream
Known Direct Subclasses

Class Overview

FileOutputStream is a class whose underlying stream is represented by a file in the operating system. The bytes that are written to this stream are passed directly to the underlying operating system equivalent function. Since overhead may be high in writing to the OS, FileOutputStreams are usually wrapped with a BufferedOutputStream to reduce the number of times the OS is called.

BufferedOutputStream buf = new BufferedOutputStream(new FileOutputStream("aFile.txt"));

See Also

Summary

Public Constructors
FileOutputStream(File file)
Constructs a new FileOutputStream on the File file.
FileOutputStream(File file, boolean append)
Constructs a new FileOutputStream on the File file.
FileOutputStream(FileDescriptor fd)
Constructs a new FileOutputStream on the FileDescriptor fd.
FileOutputStream(String filename)
Constructs a new FileOutputStream on the file named fileName.
FileOutputStream(String filename, boolean append)
Constructs a new FileOutputStream on the file named filename.
Public Methods
void close()
Close the FileOutputStream.
FileChannel getChannel()
Returns the FileChannel equivalent to this output stream.
final FileDescriptor getFD()
Returns a FileDescriptor which represents the lowest level representation of a OS stream resource.
void write(byte[] buffer)
Writes the entire contents of the byte array buffer to this FileOutputStream.
void write(int oneByte)
Writes the specified byte oneByte to this FileOutputStream.
void write(byte[] buffer, int offset, int count)
Writes count bytes from the byte array buffer starting at offset to this FileOutputStream.
Protected Methods
void finalize()
Frees any resources allocated to represent this FileOutputStream before it is garbage collected.
[Expand]
Inherited Methods
From class java.io.OutputStream
From class java.lang.Object
From interface java.io.Closeable
From interface java.io.Flushable

Public Constructors

public FileOutputStream (File file)

Constructs a new FileOutputStream on the File file. If the file exists, it is written over. See the constructor which can append to the file if so desired.

Parameters
file the File on which to stream reads.
Throws
FileNotFoundException If the file cannot be opened for writing.
See Also

public FileOutputStream (File file, boolean append)

Constructs a new FileOutputStream on the File file. If the file exists, it is written over. The parameter append determines whether or not the file is opened and appended to or just opened empty.

Parameters
file the File on which to stream reads.
append a boolean indicating whether or not to append to an existing file.
Throws
FileNotFoundException If the file cannot be opened for writing.
See Also

public FileOutputStream (FileDescriptor fd)

Constructs a new FileOutputStream on the FileDescriptor fd. The file must already be open, therefore no FileIOException will be thrown.

Parameters
fd the FileDescriptor on which to stream writes.
See Also

public FileOutputStream (String filename)

Constructs a new FileOutputStream on the file named fileName. If the file exists, it is written over. See the constructor which can append to the file if so desired. The fileName may be absolute or relative to the System property "user.dir".

Parameters
filename the file on which to stream writes.
Throws
FileNotFoundException If the filename cannot be opened for writing.

public FileOutputStream (String filename, boolean append)

Constructs a new FileOutputStream on the file named filename. If the file exists, it is written over. The parameter append determines whether or not the file is opened and appended to or just opened empty. The filename may be absolute or relative to the System property "user.dir".

Parameters
filename the file on which to stream writes.
append a boolean indicating whether or not to append to an existing file.
Throws
FileNotFoundException If the filename cannot be opened for writing.

Public Methods

public void close ()

Close the FileOutputStream. This implementation closes the underlying OS resources allocated to represent this stream.

Throws
IOException If an error occurs attempting to close this FileOutputStream.

public FileChannel getChannel ()

Returns the FileChannel equivalent to this output stream.

The file channel is write-only and has an initial position within the file that is the same as the current position of this FileOutputStream within the file. All changes made to the underlying file descriptor state via the channel are visible by the output stream and vice versa.

Returns
  • the file channel representation for this FileOutputStream.

public final FileDescriptor getFD ()

Returns a FileDescriptor which represents the lowest level representation of a OS stream resource.

Returns
  • a FileDescriptor representing this FileOutputStream.
Throws
IOException If the Stream is already closed and there is no FileDescriptor.

public void write (byte[] buffer)

Writes the entire contents of the byte array buffer to this FileOutputStream.

Parameters
buffer the buffer to be written
Throws
IOException If an error occurs attempting to write to this FileOutputStream.

public void write (int oneByte)

Writes the specified byte oneByte to this FileOutputStream. Only the low order byte of oneByte is written.

Parameters
oneByte the byte to be written
Throws
IOException If an error occurs attempting to write to this FileOutputStream.

public void write (byte[] buffer, int offset, int count)

Writes count bytes from the byte array buffer starting at offset to this FileOutputStream.

Parameters
buffer the buffer to be written
offset offset in buffer to get bytes
count number of bytes in buffer to write
Throws
IOException If an error occurs attempting to write to this FileOutputStream.
IndexOutOfBoundsException If offset or count are outside of bounds.
NullPointerException If buffer is null.

Protected Methods

protected void finalize ()

Frees any resources allocated to represent this FileOutputStream before it is garbage collected. This method is called from the Java Virtual Machine.

Throws
IOException If an error occurs attempting to finalize this FileOutputStream.