GeezerVison is showing docs.oracle.com — Writer (Java SE 25 & JDK 25)
Class Writer
- All Implemented Interfaces:
Closeable, Flushable, Appendable, AutoCloseable
- Direct Known Subclasses:
BufferedWriter, CharArrayWriter, FilterWriter, OutputStreamWriter, PipedWriter, PrintWriter, StringWriter
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:
-
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Field Summary
Fields
Modifier and Type
Field
Description
The object used to synchronize operations on this stream.
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Constructor Summary
Constructors
Modifier
Constructor
Description
protected
Creates a new character-stream writer whose critical sections will
synchronize on the writer itself.
protected
Creates a new character-stream writer whose critical sections will
synchronize on the given object.
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Method Summary
Modifier and Type
Method
Description
Appends the specified character to this writer.
Appends the specified character sequence to this writer.
Appends a subsequence of the specified character sequence to this writer.
abstract void
Closes the stream, flushing it first.
abstract void
Returns a new Writer which discards all characters.
void
Writes an array of characters.
abstract void
write(char[] cbuf,
int off,
int len)
Writes a portion of an array of characters.
void
Writes a single character.
void
void
Writes a portion of a string.
Methods declared in class Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Field Details
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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.
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Constructor Details
-
Writer
protected Writer()
Creates a new character-stream writer whose critical sections will
synchronize on the writer itself.
-
Writer
Creates a new character-stream writer whose critical sections will
synchronize on the given object.
- Parameters:
lock - Object to synchronize on
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Method Details
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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
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write
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
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write
Writes an array of characters.
- Parameters:
cbuf - Array of characters to be written
- Throws:
IOException - If an I/O error occurs
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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
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write
Writes a string.
- Parameters:
str - String to be written
- Throws:
IOException - If an I/O error occurs
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write
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
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append
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
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
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append
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
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
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
- 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
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flush
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
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close
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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