FileOutputStream - JRE Emulation | JRE Emulation
public class

FileOutputStream

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

Class Overview

An output stream that writes bytes to a file. If the output file exists, it can be replaced or appended to. If it does not exist, a new file will be created.

   File file = ...
   OutputStream out = null;
   try {
     out = new BufferedOutputStream(new FileOutputStream(file));
     ...
   } finally {
     if (out != null) {
       out.close();
     }
   }
 

This stream is not buffered. Most callers should wrap this stream with a BufferedOutputStream.

Use FileWriter to write characters, as opposed to bytes, to a file.

Summary

Public Constructors
FileOutputStream(File file)
Constructs a new FileOutputStream that writes to file.
FileOutputStream(File file, boolean append)
Constructs a new FileOutputStream that writes to file.
FileOutputStream(FileDescriptor fd)
Constructs a new FileOutputStream that writes to fd.
FileOutputStream(String path)
Constructs a new FileOutputStream that writes to path.
FileOutputStream(String path, boolean append)
Constructs a new FileOutputStream that writes to path.
Public Methods
void close()
Closes this output stream and releases any system resources associated with this stream.
FileChannel getChannel()
Returns a write-only FileChannel that shares its position with this stream.
final FileDescriptor getFD()
Returns the underlying file descriptor.
void write(byte[] buffer, int byteOffset, int byteCount)
Writes len bytes from the specified byte array starting at offset off to this output stream.
void write(int oneByte)
Writes the specified byte to this output stream.
Protected Methods
void finalize()
Invoked when the garbage collector has detected that this instance is no longer reachable.
Inherited Methods
[Expand]
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

public FileOutputStream (File file)

Constructs a new FileOutputStream that writes to file. The file will be truncated if it exists, and created if it doesn't exist.

Throws
FileNotFoundException if file cannot be opened for writing.

public FileOutputStream (File file, boolean append)

Constructs a new FileOutputStream that writes to file. If append is true and the file already exists, it will be appended to; otherwise it will be truncated. The file will be created if it does not exist.

Throws
FileNotFoundException if the file cannot be opened for writing.

public FileOutputStream (FileDescriptor fd)

Constructs a new FileOutputStream that writes to fd.

Throws
NullPointerException if fd is null.

public FileOutputStream (String path)

Constructs a new FileOutputStream that writes to path. The file will be truncated if it exists, and created if it doesn't exist.

Throws
FileNotFoundException if file cannot be opened for writing.

public FileOutputStream (String path, boolean append)

Constructs a new FileOutputStream that writes to path. If append is true and the file already exists, it will be appended to; otherwise it will be truncated. The file will be created if it does not exist.

Throws
FileNotFoundException if the file cannot be opened for writing.

Public Methods

public void close ()

Closes this output stream and releases any system resources associated with this stream. The general contract of close is that it closes the output stream. A closed stream cannot perform output operations and cannot be reopened.

The close method of OutputStream does nothing.

Throws
IOException

public FileChannel getChannel ()

Returns a write-only FileChannel that shares its position with this stream.

public final FileDescriptor getFD ()

Returns the underlying file descriptor.

Throws
IOException

public void write (byte[] buffer, int byteOffset, int byteCount)

Writes len bytes from the specified byte array starting at offset off to this output stream. The general contract for write(b, off, len) is that some of the bytes in the array b are written to the output stream in order; element b[off] is the first byte written and b[off+len-1] is the last byte written by this operation.

The write method of OutputStream calls the write method of one argument on each of the bytes to be written out. Subclasses are encouraged to override this method and provide a more efficient implementation.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

Parameters
buffer the data.
byteOffset the start offset in the data.
byteCount the number of bytes to write.
Throws
IOException

public void write (int oneByte)

Writes the specified byte to this output stream. The general contract for write is that one byte is written to the output stream. The byte to be written is the eight low-order bits of the argument b. The 24 high-order bits of b are ignored.

Subclasses of OutputStream must provide an implementation for this method.

Parameters
oneByte the byte.
Throws
IOException

Protected Methods

protected void finalize ()

Invoked when the garbage collector has detected that this instance is no longer reachable. The default implementation does nothing, but this method can be overridden to free resources.

Note that objects that override finalize are significantly more expensive than objects that don't. Finalizers may be run a long time after the object is no longer reachable, depending on memory pressure, so it's a bad idea to rely on them for cleanup. Note also that finalizers are run on a single VM-wide finalizer thread, so doing blocking work in a finalizer is a bad idea. A finalizer is usually only necessary for a class that has a native peer and needs to call a native method to destroy that peer. Even then, it's better to provide an explicit close method (and implement Closeable), and insist that callers manually dispose of instances. This works well for something like files, but less well for something like a BigInteger where typical calling code would have to deal with lots of temporaries. Unfortunately, code that creates lots of temporaries is the worst kind of code from the point of view of the single finalizer thread.

If you must use finalizers, consider at least providing your own ReferenceQueue and having your own thread process that queue.

Unlike constructors, finalizers are not automatically chained. You are responsible for calling super.finalize() yourself.

Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread. See Effective Java Item 7, "Avoid finalizers" for more.

Throws
IOException