Module java.base

Package java.io

Class OutputStreamWriter

java.lang.Object

java.io.Writer

java.io.OutputStreamWriter

All Implemented Interfaces:

Closeable, Flushable, Appendable, AutoCloseable

Direct Known Subclasses:

FileWriter

public class OutputStreamWriter
extends Writer

An OutputStreamWriter is a bridge from character streams to byte streams: Characters written to it are encoded into bytes using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the default charset may be accepted.

Each invocation of a write() method causes the encoding converter to be invoked on the given character(s). The resulting bytes are accumulated in a buffer before being written to the underlying output stream. Note that the characters passed to the write() methods are not buffered.

For top efficiency, consider wrapping an OutputStreamWriter within a BufferedWriter so as to avoid frequent converter invocations. For example:

    Writer out = new BufferedWriter(new OutputStreamWriter(anOutputStream));

A surrogate pair is a character represented by a sequence of two char values: A high surrogate in the range '\uD800' to '\uDBFF' followed by a low surrogate in the range '\uDC00' to '\uDFFF'.

A malformed surrogate element is a high surrogate that is not followed by a low surrogate or a low surrogate that is not preceded by a high surrogate.

This class always replaces malformed surrogate elements and unmappable character sequences with the charset's default substitution sequence. The CharsetEncoder class should be used when more control over the encoding process is required.

Since:

1.1

See Also:

• BufferedWriter
• OutputStream
• Charset

Field Summary

Fields declared in class java.io.Writer

lock

Constructor Summary

Constructors

Constructor	Description
OutputStreamWriter(OutputStream out)	Creates an OutputStreamWriter that uses the default character encoding, or where out is a PrintStream, the charset used by the print stream.
OutputStreamWriter(OutputStream out, String charsetName)	Creates an OutputStreamWriter that uses the named charset.
OutputStreamWriter(OutputStream out, Charset cs)	Creates an OutputStreamWriter that uses the given charset.
OutputStreamWriter(OutputStream out, CharsetEncoder enc)	Creates an OutputStreamWriter that uses the given charset encoder.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the stream, flushing it first.
void	flush()	Flushes the stream.
String	getEncoding()	Returns the name of the character encoding being used by this stream.
void	write(char[] cbuf, int off, int len)	Writes a portion of an array of characters.
void	write(int c)	Writes a single character.
void	write(String str, int off, int len)	Writes a portion of a string.

Methods declared in class java.io.Writer

append, append, append, nullWriter, write, write

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

OutputStreamWriter

public OutputStreamWriter(OutputStream out,
 String charsetName)
                   throws UnsupportedEncodingException

Creates an OutputStreamWriter that uses the named charset.

Parameters:

out - An OutputStream

charsetName - The name of a supported charset

Throws:

UnsupportedEncodingException - If the named encoding is not supported

OutputStreamWriter

public OutputStreamWriter(OutputStream out)

Creates an OutputStreamWriter that uses the default character encoding, or where out is a PrintStream, the charset used by the print stream.

Parameters:

out - An OutputStream

See Also:

• Charset.defaultCharset()

OutputStreamWriter

public OutputStreamWriter(OutputStream out,
 Charset cs)

Creates an OutputStreamWriter that uses the given charset.

Parameters:

out - An OutputStream

cs - A charset

Since:

1.4

OutputStreamWriter

public OutputStreamWriter(OutputStream out,
 CharsetEncoder enc)

Creates an OutputStreamWriter that uses the given charset encoder.

Parameters:

out - An OutputStream

enc - A charset encoder

Since:

1.4

Method Details

getEncoding

public String getEncoding()

Returns the name of the character encoding being used by this stream.

If the encoding has an historical name then that name is returned; otherwise the encoding's canonical name is returned.

If this instance was created with the OutputStreamWriter(OutputStream, String) constructor then the returned name, being unique for the encoding, may differ from the name passed to the constructor. This method may return null if the stream has been closed.

Returns:

The historical name of this encoding, or possibly null if the stream has been closed

See Also:

• Charset

write

public void write(int c)
           throws IOException

Writes a single character.

Overrides:

write in class Writer

Parameters:

c - int specifying a character to be written

Throws:

IOException - If an I/O error occurs

write

public void write(char[] cbuf,
 int off,
 int len)
           throws IOException

Writes a portion of an array of characters.

Specified by:

write in class Writer

Parameters:

cbuf - Buffer of characters

off - Offset from which to start writing characters

len - Number of characters to write

Throws:

IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given array

IOException - If an I/O error occurs

write

public void write(String str,
 int off,
 int len)
           throws IOException

Writes a portion of a string.

Overrides:

write in class Writer

Parameters:

str - A String

off - Offset from which to start writing characters

len - Number of characters to write

Throws:

IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given string

IOException - If an I/O error occurs

flush

public void flush()
           throws IOException

Flushes the stream.

Specified by:

flush in interface Flushable

Specified by:

flush in class Writer

Throws:

IOException - If an I/O error occurs

close

public void close()
           throws IOException

Description copied from class: Writer

Closes the stream, flushing it first. Once the stream has been closed, further write() or flush() invocations will cause an IOException to be thrown. Closing a previously closed stream has no effect.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in class Writer

Throws:

IOException - If an I/O error occurs