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:

JDK1.1

See Also:
Writer, BufferedWriter, CharArrayWriter, FilterWriter, OutputStreamWriter, FileWriter, PipedWriter, PrintWriter, StringWriter, Reader

Field Summary
Fields
Modifier and Type Field and Description

protected Object lock
The object used to synchronize operations on this stream.

Writer (Java Platform SE 7 ) Home of API Java Contents Haut

Constructor Summary

Constructors
Modifier	Constructor and 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.

Writer (Java Platform SE 7 ) Home of API Java Contents Haut

Method Summary

Methods
Modifier and Type	Method and 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.
`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.

Writer (Java Platform SE 7 ) Home of API Java Contents Haut

Methods inherited from 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
  - 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:
    
    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.
    
    Parameters:
    str - A String
    off - Offset from which to start writing characters
    len - Number of characters to write
    
    Throws:
    
    IndexOutOfBoundsException - 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) 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
  - 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 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
    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 Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Throws:
    
    IOException - If an I/O error occurs

Document created the 11/06/2005, last modified the 04/03/2020
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References

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Class Writer

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