BufferedWriter (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档
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Java™ Platform Standard Ed. 6 |
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java.io
Class BufferedWriter
java.lang.Objectjava.io.Writer
- All Implemented Interfaces:
- Closeable, Flushable, Appendable
public class BufferedWriter
- extends Writer
Writes 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.
- Since:
- JDK1.1
- See Also:
PrintWriter,FileWriter,OutputStreamWriter
| Field Summary |
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| Fields inherited from class java.io.Writer |
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lock |
| Constructor Summary | |
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BufferedWriter(Writer out)
Creates a buffered character-output stream that uses a default-sized output buffer. |
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BufferedWriter(Writer out,
int sz)
Creates a new buffered character-output stream that uses an output buffer of the given size. |
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| Method Summary | |
|---|---|
void |
close()
Closes the stream, flushing it first. |
void |
flush()
Flushes the stream. |
void |
newLine()
Writes a line separator. |
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 s,
int off,
int len)
Writes a portion of a String. |
| Methods inherited from class java.io.Writer |
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append, append, append, write, write |
| Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
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BufferedWriter
public BufferedWriter(Writer out)
- Creates a buffered character-output stream that uses a default-sized
output buffer.
- Parameters:
out- A Writer
BufferedWriter
public BufferedWriter(Writer out, int sz)
- Creates a new buffered character-output stream that uses an output
buffer of the given size.
- Parameters:
out- A Writersz- Output-buffer size, a positive integer- Throws:
IllegalArgumentException- If sz is <= 0
| Method Detail |
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write
public void write(int c)
throws IOException
- Writes a single character.
- 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.
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 arrayoff- Offset from which to start reading characterslen- Number of characters to write- Throws:
IOException- If an I/O error occurs
write
public void write(String s, int off, int len) throws IOException
- Writes a portion of a String.
If the value of the len parameter is negative then no characters are written. This is contrary to the specification of this method in the superclass, which requires that an
IndexOutOfBoundsExceptionbe thrown.- Parameters:
s- String to be writtenoff- Offset from which to start reading characterslen- Number of characters to be written- Throws:
IOException- If an I/O error occurs
newLine
public void newLine()
throws IOException
- Writes 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
- Flushes the stream.
- 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.
- Throws:
IOException- If an I/O error occurs
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Java™ Platform Standard Ed. 6 |
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For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright 2006 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.