- java.lang.Object
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- java.io.Writer
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- java.io.BufferedWriter
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- All Implemented Interfaces:
- Closeable, Flushable, Appendable, AutoCloseable
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.
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Field Summary
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Fields inherited from class java.io.Writer
lock
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Constructor Summary
Constructors Constructor and Description BufferedWriter(Writer out)
Creates a buffered character-output stream that uses a default-sized output buffer.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
Methods Modifier and Type Method and Description 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.
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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
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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
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Method Detail
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write
public void write(int c) throws IOException
Writes a single character.- Overrides:
write
in classWriter
- Parameters:
c
- int specifying a character to be written- Throws:
IOException
- If an I/O error occurs
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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
BufferedWriter
s will not copy data unnecessarily.- Specified by:
write
in classWriter
- 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
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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
IndexOutOfBoundsException
be thrown.- Overrides:
write
in classWriter
- 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
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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
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flush
public void flush() throws IOException
Flushes the stream.- Specified by:
flush
in interfaceFlushable
- Specified by:
flush
in classWriter
- Throws:
IOException
- If an I/O error occurs
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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 interfaceCloseable
- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in classWriter
- Throws:
IOException
- If an I/O error occurs
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