java.io
Class Writer

java.lang.Object
  extended by java.io.Writer
All Implemented Interfaces:
Closeable, Flushable, Appendable
Direct Known Subclasses:
BufferedWriter, CharArrayWriter, FilterWriter, OutputStreamWriter, PipedWriter, PrintWriter, StringWriter

public abstract class Writer
extends Object
implements Appendable, Closeable, Flushable

This abstract class forms the base of the hierarchy of classes that write output as a stream of chars. It provides a common set of methods for writing chars to stream. Subclasses implement and/or extend these methods to write chars in a particular manner or to a particular destination such as a file on disk or network connection.


Field Summary
protected  Object lock
          This is the object used to synchronize criticial code sections for thread safety.
 
Constructor Summary
protected Writer()
          This is the default no-argument constructor for this class.
protected Writer(Object lock)
          This method initializes a Writer that will synchronize on the specified Object.
 
Method Summary
 Writer append(char c)
          Appends the Unicode character, c, to this Appendable object.
 Writer append(CharSequence cs)
          Appends the specified sequence of Unicode characters to this Appendable object.
 Writer append(CharSequence cs, int start, int end)
          Appends the specified subsequence of Unicode characters to this Appendable object, starting and ending at the specified positions within the sequence.
abstract  void close()
          This method closes the stream.
abstract  void flush()
          This method forces any data that may have been buffered to be written to the underlying output device.
 void write(char[] buf)
          This method all the writes char from the passed array to the output stream.
abstract  void write(char[] buf, int offset, int len)
          This method writes len char from the specified array buf starting at index offset into the array.
 void write(int b)
          This method writes a single char to the output stream.
 void write(String str)
          This method writes all the characters in a String to the output.
 void write(String str, int offset, int len)
          This method writes len chars from the String starting at position offset.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

lock

protected Object lock
This is the object used to synchronize criticial code sections for thread safety. Subclasses should use this field instead of using synchronized methods or explicity synchronizations on this

Constructor Detail

Writer

protected Writer()
This is the default no-argument constructor for this class. This method will set up the class to synchronize criticial sections on itself.


Writer

protected Writer(Object lock)
This method initializes a Writer that will synchronize on the specified Object.

Parameters:
lock - The Object to use for synchronizing critical sections. Must not be null.
Method Detail

flush

public abstract void flush()
                    throws IOException
This method forces any data that may have been buffered to be written to the underlying output device. Please note that the host environment might perform its own buffering unbeknowst to Java. In that case, a write made (for example, to a disk drive) might be cached in OS buffers instead of actually being written to disk.

Specified by:
flush in interface Flushable
Throws:
IOException - If an error occurs

close

public abstract void close()
                    throws IOException
This method closes the stream. Any internal or native resources associated with this stream are freed. Any subsequent attempt to access the stream might throw an exception.

This method in this class does nothing.

Specified by:
close in interface Closeable
Throws:
IOException - If an error occurs

write

public void write(int b)
           throws IOException
This method writes a single char to the output stream.

Parameters:
b - The char to be written to the output stream, passed as an int
Throws:
IOException - If an error occurs

write

public void write(char[] buf)
           throws IOException
This method all the writes char from the passed array to the output stream. This method is equivalent to write(buf, 0, buf.length) which is exactly how it is implemented in this class.

Parameters:
buf - The array of char to write
Throws:
IOException - If an error occurs

write

public abstract void write(char[] buf,
                           int offset,
                           int len)
                    throws IOException
This method writes len char from the specified array buf starting at index offset into the array.

Subclasses must provide an implementation of this abstract method.

Parameters:
buf - The array of char to write from
offset - The index into the array to start writing from
len - The number of char to write
Throws:
IOException - If an error occurs

write

public void write(String str)
           throws IOException
This method writes all the characters in a String to the output.

Parameters:
str - The String whose chars are to be written.
Throws:
IOException - If an error occurs

write

public void write(String str,
                  int offset,
                  int len)
           throws IOException
This method writes len chars from the String starting at position offset.

Parameters:
str - The String that is to be written
offset - The character offset into the String to start writing from
len - The number of chars to write
Throws:
IOException - If an error occurs

append

public Writer append(char c)
              throws IOException
Description copied from interface: Appendable
Appends the Unicode character, c, to this Appendable object.

Specified by:
append in interface Appendable
Parameters:
c - the character to append.
Returns:
a reference to this object.
Throws:
IOException - if an I/O error occurs.
Since:
1.5

append

public Writer append(CharSequence cs)
              throws IOException
Description copied from interface: Appendable
Appends the specified sequence of Unicode characters to this Appendable object. The entire sequence may not be appended, if constrained by the underlying implementation. For example, a buffer may reach its size limit before the entire sequence is appended.

Specified by:
append in interface Appendable
Parameters:
cs - the character sequence to append. If seq is null, then the string "null" (the string representation of null) is appended.
Returns:
a reference to this object.
Throws:
IOException - if an I/O error occurs.
Since:
1.5

append

public Writer append(CharSequence cs,
                     int start,
                     int end)
              throws IOException
Description copied from interface: Appendable
Appends the specified subsequence of Unicode characters to this Appendable object, starting and ending at the specified positions within the sequence. The entire sequence may not be appended, if constrained by the underlying implementation. For example, a buffer may reach its size limit before the entire sequence is appended. The behaviour of this method matches the behaviour of append(seq.subSequence(start,end)) when the sequence is not null.

Specified by:
append in interface Appendable
Parameters:
cs - the character sequence to append. If seq is null, then the string "null" (the string representation of null) is appended.
start - the index of the first Unicode character to use from the sequence.
end - the index of the last Unicode character to use from the sequence.
Returns:
a reference to this object.
Throws:
IOException - if an I/O error occurs.
Since:
1.5