Class Writer
- 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:
-
BufferedWriter
,CharArrayWriter
,FilterWriter
,OutputStreamWriter
,FileWriter
,PipedWriter
,PrintWriter
,StringWriter
,Reader
Field Summary
Modifier and Type | Field | Description |
---|---|---|
protected Object | lock | The object used to synchronize operations on this stream. |
Constructor Summary
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
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 |
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 Detail
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 Detail
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 Detail
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 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 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 ifoff
is negative, orlen
is negative, oroff + 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)
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 interfaceAppendable
- Parameters:
-
csq
- The character sequence to append. Ifcsq
isnull
, 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. Appendable
.
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 interfaceAppendable
- Parameters:
-
csq
- The character sequence from which a subsequence will be appended. Ifcsq
isnull
, then characters will be appended as ifcsq
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
- Ifstart
orend
are negative,start
is greater thanend
, orend
is greater thancsq.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
out.write(c)
- Specified by:
-
append
in interfaceAppendable
- 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 interfaceFlushable
- 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 interfaceAutoCloseable
- Specified by:
-
close
in interfaceCloseable
- Throws:
-
IOException
- If an I/O error occurs