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.
Writer
, BufferedWriter
, CharArrayWriter
, FilterWriter
, OutputStreamWriter
, FileWriter
, PipedWriter
, PrintWriter
, StringWriter
, Reader
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.
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.
lock
- Object to synchronize onpublic 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.
c
- int specifying a character to be writtenIOException
- If an I/O error occurspublic void write(char[] cbuf) throws IOException
Writes an array of characters.
cbuf
- Array of characters to be writtenIOException
- If an I/O error occurspublic abstract void write(char[] cbuf, int off, int len) throws IOException
Writes a portion of an array of characters.
cbuf
- Array of charactersoff
- Offset from which to start writing characterslen
- Number of characters to writeIOException
- If an I/O error occurspublic void write(String str) throws IOException
Writes a string.
str
- String to be writtenIOException
- If an I/O error occurspublic void write(String str, int off, int len) throws IOException
Writes a portion of a string.
str
- A Stringoff
- Offset from which to start writing characterslen
- Number of characters to writeIndexOutOfBoundsException
- If off
is negative, or len
is negative, or off+len
is negative or greater than the length of the given stringIOException
- If an I/O error occurspublic 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.
append
in interface Appendable
csq
- The character sequence to append. If csq
is null
, then the four characters "null"
are appended to this writer.IOException
- If an I/O error occurspublic 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())
append
in interface Appendable
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 subsequenceend
- The index of the character following the last character in the subsequenceIndexOutOfBoundsException
- If start
or end
are negative, start
is greater than end
, or end
is greater than csq.length()
IOException
- If an I/O error occurspublic 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)
append
in interface Appendable
c
- The 16-bit character to appendIOException
- If an I/O error occurspublic 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.
flush
in interface Flushable
IOException
- If an I/O error occurspublic 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.
close
in interface Closeable
close
in interface AutoCloseable
IOException
- If an I/O error occurs
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