Class BufferedWriter
- java.lang.Object
-
- java.io.Writer
-
- java.io.BufferedWriter
- 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.
- Since:
- 1.1
- See Also:
-
PrintWriter
,FileWriter
,OutputStreamWriter
,Files.newBufferedWriter(java.nio.file.Path, java.nio.charset.Charset, java.nio.file.OpenOption...)
Field Summary
Fields declared in class java.io.Writer
lock
Constructor Summary
Constructor | 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. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
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 declared in class java.io.Writer
append, append, append, close, nullWriter, write, write
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
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 Writer -
sz
- Output-buffer size, a positive integer - Throws:
-
IllegalArgumentException
- Ifsz <= 0
Method Detail
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
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 array -
off
- Offset from which to start reading characters -
len
- Number of characters to write - Throws:
-
IndexOutOfBoundsException
- Ifoff
is negative, orlen
is negative, oroff + len
is negative or greater than the length of the given array -
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.
- Overrides:
-
write
in classWriter
- Implementation Requirements:
- While the specification of this method in the superclass recommends that an
IndexOutOfBoundsException
be thrown iflen
is negative oroff + len
is negative, the implementation in this class does not throw such an exception in these cases but instead simply writes no characters. - Parameters:
-
s
- String to be written -
off
- Offset from which to start reading characters -
len
- Number of characters to be written - Throws:
-
IndexOutOfBoundsException
- Ifoff
is negative, oroff + len
is greater than the length of the given string -
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.
- Specified by:
-
flush
in interfaceFlushable
- Specified by:
-
flush
in classWriter
- Throws:
-
IOException
- If an I/O error occurs