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java.lang.Object

java.io.Writer

All Implemented Interfaces:: Closeable, Flushable, Appendable, AutoCloseable

Direct Known Subclasses:: BufferedWriter, CharArrayWriter, FilterWriter, OutputStreamWriter, PipedWriter, PrintWriter, StringWriter

public abstract class Writer extends Object implements Appendable, Closeable, Flushable

Abstract class for writing to character streams. The only methods that a subclass must implement are write(char[], int, int), flush(), and close(). Most subclasses, however, will override some of the methods defined here in order to provide higher efficiency, additional functionality, or both.

Since:

1.1

See Also:

Field Summary

Fields

Modifier and Type

Field

Description

protected Object

lock

The object used to synchronize operations on this stream.
Constructor Summary

Constructors

Modifier

Constructor

Description

protected

Writer()

Creates a new character-stream writer whose critical sections will synchronize on the writer itself.

protected

Writer(Object lock)

Creates a new character-stream writer whose critical sections will synchronize on the given object.
Method Summary

All MethodsStatic MethodsInstance MethodsAbstract MethodsConcrete Methods

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.

abstract void

close()

Closes the stream, flushing it first.

abstract void

flush()

Flushes the stream.

static Writer

nullWriter()

Returns a new Writer which discards all characters.

void

write(char[] cbuf)

Writes an array of characters.

abstract 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 str)

Writes a string.

void

write(String str, int off, int len)

Writes a portion of a string.

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

Field Details
- lock
  
  protected Object lock
  
  The object used to synchronize operations on this stream. For efficiency, a character-stream object may use an object other than itself to protect critical sections. A subclass should therefore use the object in this field rather than this or a synchronized method.
Constructor Details
- Writer
  
  protected Writer()
  
  Creates a new character-stream writer whose critical sections will synchronize on the writer itself.
- Writer
  
  protected Writer(Object lock)
  
  Creates a new character-stream writer whose critical sections will synchronize on the given object.
  
  Parameters:
  
  lock - Object to synchronize on
Method Details
- nullWriter
  
  public static Writer nullWriter()
  
  Returns a new Writer which discards all characters. The returned stream is initially open. The stream is closed by calling the close() method. Subsequent calls to close() have no effect.
  While the stream is open, the append(char), append(CharSequence), append(CharSequence, int, int), flush(), write(int), write(char[]), and write(char[], int, int) methods do nothing. After the stream has been closed, these methods all throw IOException.
  The object used to synchronize operations on the returned Writer is not specified.
  
  Returns:
  
  a Writer which discards all characters
  
  Since:
  
  11
- write
  
  public void write(int c) throws IOException
  
  Writes a single character. The character to be written is contained in the 16 low-order bits of the given integer value; the 16 high-order bits are ignored.
  Subclasses that intend to support efficient single-character output should override this method.
  
  Parameters:
  
  c - int specifying a character to be written
  
  Throws:
  
  IOException - If an I/O error occurs
- write
  
  public void write(char[] cbuf) throws IOException
  
  Writes an array of characters.
  
  Parameters:
  
  cbuf - Array of characters to be written
  
  Throws:
  
  IOException - If an I/O error occurs
- write
  
  public abstract void write(char[] cbuf, int off, int len) throws IOException
  
  Writes a portion of an array of characters.
  
  Parameters:
  
  cbuf - Array of characters
  
  off - Offset from which to start writing characters
  
  len - Number of characters to write
  
  Throws:
  
  IndexOutOfBoundsException - Implementations should throw this exception 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 str) throws IOException
  
  Writes a string.
  
  Parameters:
  
  str - String to be written
  
  Throws:
  
  IOException - If an I/O error occurs
- write
  
  public void write(String str, int off, int len) throws IOException
  
  Writes a portion of a string.
  
  Implementation Requirements:
  
  The implementation in this class throws an IndexOutOfBoundsException for the indicated conditions; overriding methods may choose to do otherwise.
  
  Parameters:
  
  str - A String
  
  off - Offset from which to start writing characters
  
  len - Number of characters to write
  
  Throws:
  
  IndexOutOfBoundsException - Implementations should throw this exception if off is negative, or len is negative, or off + len is negative or greater than the length of the given string
  
  IOException - If an I/O error occurs
- append
  public Writer append(CharSequence csq) throws IOException
  Appends the specified character sequence to this writer.
  An invocation of this method of the form out.append(csq) when csq is not null, behaves in exactly the same way as the invocation
  Copy [Copy snippet]
  out.write(csq.toString())
  Depending on the specification of toString for the character sequence csq, the entire sequence may not be appended. For instance, invoking the toString method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.
  Specified by:
  
  append in interface Appendable
  
  Parameters:
  
  csq - The character sequence to append. If csq is null, then the four characters "null" are appended to this writer.
  
  Returns:
  
  This writer
  
  Throws:
  
  IOException - If an I/O error occurs
  
  Since:
  
  1.5
- append
  public Writer append(CharSequence csq, int start, int end) throws IOException
  Appends a subsequence of the specified character sequence to this writer.
  An invocation of this method of the form out.append(csq, start, end) when csq is not null behaves in exactly the same way as the invocation
  Copy [Copy snippet]
  out.write(csq.subSequence(start, end).toString())
  Specified by:
  
  append in interface Appendable
  
  Parameters:
  
  csq - The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".
  
  start - The index of the first character in the subsequence
  
  end - The index of the character following the last character in the subsequence
  
  Returns:
  
  This writer
  
  Throws:
  
  IndexOutOfBoundsException - If start or end are negative, start is greater than end, or end is greater than csq.length()
  
  IOException - If an I/O error occurs
  
  Since:
  
  1.5
- append
  public Writer append(char c) throws IOException
  Appends the specified character to this writer.
  An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation
  Copy [Copy snippet]
  out.write(c)
  Specified by:
  
  append in interface Appendable
  
  Parameters:
  
  c - The 16-bit character to append
  
  Returns:
  
  This writer
  
  Throws:
  
  IOException - If an I/O error occurs
  
  Since:
  
  1.5
- flush
  
  public abstract void flush() throws IOException
  
  Flushes the stream. If the stream has saved any characters from the various write() methods in a buffer, write them immediately to their intended destination. Then, if that destination is another character or byte stream, flush it. Thus one flush() invocation will flush all the buffers in a chain of Writers and OutputStreams.
  If the intended destination of this stream is an abstraction provided by the underlying operating system, for example a file, then flushing the stream guarantees only that bytes previously written to the stream are passed to the operating system for writing; it does not guarantee that they are actually written to a physical device such as a disk drive.
  
  Specified by:
  
  flush in interface Flushable
  
  Throws:
  
  IOException - If an I/O error occurs
- close
  
  public abstract void close() throws IOException
  
  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
  
  Throws:
  
  IOException - If an I/O error occurs

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Class Writer

Field Summary

Constructor Summary

Method Summary

Methods declared in class java.lang.Object

Field Details

lock

Constructor Details

Writer

Writer

Method Details

nullWriter

write

write

write

write

write

append

append

append

flush

close