PipedWriter.java (flush): Throw exception if stream closed.

* java/io/PipedWriter.java (flush): Throw exception if stream
	closed.
	* java/io/OutputStreamWriter.java (write): Throw exception if
	stream closed.
	(writeChars): Don't throw exception if stream closed.
	* java/io/CharArrayWriter.java (closed): New field.
	(close): Set it.
	(flush): Throw exception if stream closed.
	(reset): Synchronize on correct lock.  Allow stream to be
	reopened.
	(toCharArray, toString, writeTo): Synchronize.
	(write): Throwe exception if stream closed.
	* java/io/BufferedWriter.java (close): Clear `buffer'.
	(flush): Throw IOException if stream is closed.
	(write): Likewise.

From-SVN: r39927

libjava/java/io/PipedWriter.java

@@ -142,8 +142,10 @@ public class PipedWriter extends Writer
     *           had read all available data. Thats not the case - this method
     *           appears to be a no-op?
     */
-  public void flush()
+  public void flush() throws IOException
   {
+    if (closed)
+      throw new IOException ("Pipe closed");
   }
   
   /**