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BufferedWriter (Java SE 26 & JDK 26)

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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,

Copy 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:

Field Summary

Fields declared in class Writer
lock

Modifier and Type

Field

Description

protected Object

lock

The object used to synchronize operations on this stream.
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 Writer
append, append, append, nullWriter, write, write

Modifier and Type

Method

Description

Writer

append(char c)

Appends the specified character to this writer.

Writer

append(CharSequence csq)

Appends the specified character sequence to this writer.

Writer

append(CharSequence csq, int start, int end)

Appends a subsequence of the specified character sequence to this writer.

static Writer

nullWriter()

Returns a new Writer which discards all characters.

void

write(char[] cbuf)

Writes an array of characters.

void

write(String str)

Writes a string.

Methods declared in class Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Modifier and Type

Method

Description

protected Object

clone()

Creates and returns a copy of this object.

boolean

equals(Object obj)

Indicates whether some other object is "equal to" this one.

protected void

finalize()

Deprecated, for removal: This API element is subject to removal in a future version.
Finalization is deprecated and subject to removal in a future release.

final Class<?>

getClass()

Returns the runtime class of this Object.

int

hashCode()

Returns a hash code value for this object.

final void

notify()

Wakes up a single thread that is waiting on this object's monitor.

final void

notifyAll()

Wakes up all threads that are waiting on this object's monitor.

String

toString()

Returns a string representation of the object.

final void

wait()

Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

final void

wait(long timeoutMillis)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void

wait(long timeoutMillis, int nanos)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

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

Report a bug or suggest an enhancement
For further API reference and developer documentation see the Java SE Documentation, which contains more detailed, developer-targeted descriptions with conceptual overviews, definitions of terms, workarounds, and working code examples. Other versions.
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Class BufferedWriter

Field Summary

Fields declared in class Writer

Constructor Summary

Method Summary

Methods declared in class Writer

Methods declared in class Object

Constructor Details

BufferedWriter

BufferedWriter

Method Details

write

write

write

newLine

flush

close