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Java™ Platform Standard Ed. 6 |
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java.lang.Object java.io.Writer java.io.BufferedWriter
public class BufferedWriter
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.
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. |
Method Summary | |
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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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public BufferedWriter(Writer out)
out
- A Writerpublic BufferedWriter(Writer out, int sz)
out
- A Writersz
- Output-buffer size, a positive integer
IllegalArgumentException
- If sz is <= 0Method Detail |
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public void write(int c) throws IOException
write
in class Writer
c
- int specifying a character to be written
IOException
- If an I/O error occurspublic void write(char[] cbuf, int off, int len) throws IOException
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
BufferedWriter
s will not copy data unnecessarily.
write
in class Writer
cbuf
- A character arrayoff
- Offset from which to start reading characterslen
- Number of characters to write
IOException
- If an I/O error occurspublic void write(String s, int off, int len) throws IOException
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 IndexOutOfBoundsException
be
thrown.
write
in class Writer
s
- String to be writtenoff
- Offset from which to start reading characterslen
- Number of characters to be written
IOException
- If an I/O error occurspublic void newLine() throws IOException
IOException
- If an I/O error occurspublic void flush() throws IOException
flush
in interface Flushable
flush
in class Writer
IOException
- If an I/O error occurspublic void close() throws IOException
Writer
close
in interface Closeable
close
in class Writer
IOException
- If an I/O error occurs
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Java™ Platform Standard Ed. 6 |
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