Class java.io.BufferedWriter - JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档

All Packages  Class Hierarchy  This Package  Previous  Next  Index

Class java.io.BufferedWriter

java.lang.Object
   |
   +----java.io.Writer
           |
           +----java.io.BufferedWriter

public class BufferedWriter
extends Writer

Write text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays, and strings.

The buffer size may be specified, or the default size may be accepted. The default is large enough for most purposes.

A newLine() method is provided, which uses the platform's own notion of line separator as defined by the system property line.separator. Not all platforms use the newline character ('\n') to terminate lines. Calling this method to terminate each output line is therefore preferred to writing a newline character directly.

In general, a Writer sends its output immediately to the underlying character or byte stream. Unless prompt output is required, it is advisable to wrap a BufferedWriter around any Writer whose write() operations may be costly, such as FileWriters and OutputStreamWriters. For example,

 PrintWriter out
   = new PrintWriter(new BufferedWriter(new FileWriter("foo.out")));

will buffer the PrintWriter's output to the file. Without buffering, each invocation of a print() method would cause characters to be converted into bytes that would then be written immediately to the file, which can be very inefficient.

See Also:: PrintWriter, FileWriter, OutputStreamWriter

BufferedWriter(Writer): Create a buffered character-output stream that uses a default-sized output buffer.
BufferedWriter(Writer, int): Create a new buffered character-output stream that uses an output buffer of the given size.

close(): Close the stream.
flush(): Flush the stream.
newLine(): Write a line separator.
write(char[], int, int): Write a portion of an array of characters.
write(int): Write a single character.
write(String, int, int): Write a portion of a String.

BufferedWriter

 public BufferedWriter(Writer out)

Create a buffered character-output stream that uses a default-sized output buffer.

Parameters:: out - A Writer

BufferedWriter

 public BufferedWriter(Writer out,
                       int sz)

Create a new buffered character-output stream that uses an output buffer of the given size.

Parameters:: out - A Writer; sz - Output-buffer size, a positive integer
Throws: IllegalArgumentException: If sz is <= 0

write

 public void write(int c) throws IOException

Write a single character.

Throws: IOException: If an I/O error occurs
Overrides:: write in class Writer

write

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

Write a portion of an array of characters.

Ordinarily this method stores characters from the given array into this stream's buffer, flushing the buffer to the underlying stream as needed. If the requested length is at least as large as the buffer, however, then this method will flush the buffer and write the characters directly to the underlying stream. Thus redundant BufferedWriters will not copy data unnecessarily.

Parameters:: cbuf - A character array; off - Offset from which to start reading characters; len - Number of characters to write
Throws: IOException: If an I/O error occurs
Overrides:: write in class Writer

write

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

Write a portion of a String.

Parameters:: s - String to be written; off - Offset from which to start reading characters; len - Number of characters to be written
Throws: IOException: If an I/O error occurs
Overrides:: write in class Writer

newLine

 public void newLine() throws IOException

Write a line separator. The line separator string is defined by the system property line.separator, and is not necessarily a single newline ('\n') character.

Throws: IOException: If an I/O error occurs

flush

 public void flush() throws IOException

Flush the stream.

Throws: IOException: If an I/O error occurs
Overrides:: flush in class Writer

close

 public void close() throws IOException

Close the stream.

Throws: IOException: If an I/O error occurs
Overrides:: close in class Writer

All Packages  Class Hierarchy  This Package  Previous  Next  Index

Submit a bug or feature - Version 1.1.8 of Java Platform API Specification
Java is a trademark or registered trademark of Sun Microsystems, Inc. in the US and other countries.
Copyright 1995-1999 Sun Microsystems, Inc. 901 San Antonio Road,
Palo Alto, California, 94303, U.S.A. All Rights Reserved.