- java.lang.Object
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- java.io.Writer
 
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- 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
 
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Constructor SummaryConstructors Modifier Constructor Description protectedWriter()Creates a new character-stream writer whose critical sections will synchronize on the writer itself.protectedWriter(Object lock)Creates a new character-stream writer whose critical sections will synchronize on the given object.
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Method SummaryAll Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description Writerappend(char c)Appends the specified character to this writer.Writerappend(CharSequence csq)Appends the specified character sequence to this writer.Writerappend(CharSequence csq, int start, int end)Appends a subsequence of the specified character sequence to this writer.abstract voidclose()Closes the stream, flushing it first.abstract voidflush()Flushes the stream.static WriternullWriter()Returns a newWriterwhich discards all characters.voidwrite(char[] cbuf)Writes an array of characters.abstract voidwrite(char[] cbuf, int off, int len)Writes a portion of an array of characters.voidwrite(int c)Writes a single character.voidwrite(String str)Writes a string.voidwrite(String str, int off, int len)Writes a portion of a string.
 
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Field Detail- 
lockprotected 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 thanthisor a synchronized method.
 
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Constructor Detail- 
Writerprotected Writer() Creates a new character-stream writer whose critical sections will synchronize on the writer itself.
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Writerprotected Writer(Object lock) 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 Detail- 
nullWriterpublic static Writer nullWriter() Returns a newWriterwhich discards all characters. The returned stream is initially open. The stream is closed by calling theclose()method. Subsequent calls toclose()have no effect.While the stream is open, the append(char),append(CharSequence),append(CharSequence, int, int),flush(),write(int),write(char[]), andwrite(char[], int, int)methods do nothing. After the stream has been closed, these methods all throwIOException.The objectused to synchronize operations on the returnedWriteris not specified.- Returns:
- a Writerwhich discards all characters
- Since:
- 11
 
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writepublic void write(int c) throws IOExceptionWrites 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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writepublic void write(char[] cbuf) throws IOExceptionWrites an array of characters.- Parameters:
- cbuf- Array of characters to be written
- Throws:
- IOException- If an I/O error occurs
 
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writepublic abstract void write(char[] cbuf, int off, int len) throws IOExceptionWrites 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- offis negative, or- lenis negative, or- off + lenis negative or greater than the length of the given array
- IOException- If an I/O error occurs
 
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writepublic void write(String str) throws IOException Writes a string.- Parameters:
- str- String to be written
- Throws:
- IOException- If an I/O error occurs
 
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writepublic 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
 IndexOutOfBoundsExceptionfor 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- offis negative, or- lenis negative, or- off + lenis negative or greater than the length of the given string
- IOException- If an I/O error occurs
 
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appendpublic 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 invocationout.write(csq.toString())Depending on the specification of toStringfor the character sequencecsq, the entire sequence may not be appended. For instance, invoking thetoStringmethod of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.- Specified by:
- appendin interface- Appendable
- Parameters:
- csq- The character sequence to append. If- csqis- 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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appendpublic 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)whencsqis notnullbehaves in exactly the same way as the invocationout.write(csq.subSequence(start, end).toString())- Specified by:
- appendin interface- Appendable
- Parameters:
- csq- The character sequence from which a subsequence will be appended. If- csqis- null, then characters will be appended as if- csqcontained 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- startor- endare negative,- startis greater than- end, or- endis greater than- csq.length()
- IOException- If an I/O error occurs
- Since:
- 1.5
 
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appendpublic 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 invocationout.write(c)- Specified by:
- appendin 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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flushpublic abstract void flush() throws IOExceptionFlushes 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:
- flushin interface- Flushable
- Throws:
- IOException- If an I/O error occurs
 
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closepublic abstract void close() throws IOExceptionCloses 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:
- closein interface- AutoCloseable
- Specified by:
- closein interface- Closeable
- Throws:
- IOException- If an I/O error occurs
 
 
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