1. Description
2. Field Summary
3. Constructor Summary
4. Method Summary
5. Constructor Details
   1. BufferedWriter(Writer)
   2. BufferedWriter(Writer, int)
6. Method Details
   1. write(int)
   2. write(char[], int, int)
   3. write(String, int, int)
   4. newLine()
   5. flush()
   6. close()

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,

Copy [Copy snippet]

    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.

API Note:

Once wrapped in a BufferedWriter, the underlying Writer should not be used directly nor wrapped with another writer.

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

  Constructors
  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

  All MethodsInstance MethodsConcrete Methods

  Modifier and Type

  Method

  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.

  Methods declared in class java.io.Writer

  append, append, append, nullWriter, write, write

  Methods declared in class java.lang.Object

  clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

• Constructor Details

  • 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 - If sz <= 0

• Method Details

  • write

    public void write(int c) throws IOException

    Writes a single character.

    Overrides:

    write in class Writer

    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.

    Specified by:

    write in class Writer

    Parameters:

    cbuf - A character array

    off - Offset from which to start reading characters

    len - Number of characters to write

    Throws:

    IndexOutOfBoundsException - If off is negative, or len is negative, or off + 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 class Writer

    Implementation Requirements:

    While the specification of this method in the superclass recommends that an IndexOutOfBoundsException be thrown if len is negative or off + 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 - If off is negative, or off + 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 interface Flushable

    Specified by:

    flush in class Writer

    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.

    Specified by:

    close in interface AutoCloseable

    Specified by:

    close in interface Closeable

    Specified by:

    close in class Writer

    Throws:

    IOException - If an I/O error occurs

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