Java IO.pdf - Nguyen Dang Binh

The compiler rewrites this complicated expression as:
StringBuffer sb = new StringBuffer();
sb.append("As of ");
Date d = new Date();
sb.append(d);
sb.append(" there have been over ");
sb.append(hits);
sb.append(" hits on the web site.")
String s = sb.toString();
System.out.println(s);
Java I/O
The StringBuffer append() method is overloaded in much the same way that the print()
and println() methods are so it can handle any Java data type.
PrintStream methods never throw IOExceptions. Each method in the class catches
IOExceptions. When an exception occurs, an internal flag is set to true. You test this flag
with the checkError() method:
public boolean checkError()
This method returns true if this print stream has ever encountered an error during its lifetime.
Most of the time, you just ignore this, since print streams are only used in situations where
exhaustive error checking is unnecessary.
Besides System.out and System.err, you can create new print streams with these
constructors:
public PrintStream(OutputStream out)
public PrintStream(OutputStream out, boolean autoFlush)
The out argument is just the underlying output stream. The autoFlush argument is a
boolean (true or false). If it's true, then the stream is flushed every time a linefeed (\n)
character or byte is written, a println()method is invoked, or a byte array is written.
The biggest problem with the PrintStream class is that it does not properly handle
international character sets. In Chapter 15 you'll learn about the PrintWriter class that has
much of the same functionality but can handle international character sets.
6.6 Multitarget Output Streams
As a final example, I present two slightly unusual filter output streams that direct their data to
multiple underlying streams. The TeeOutputStream class, given in Example 6.5, has not one
but two underlying streams. The TeeOutputStream does not modify the data that's written in
any way; it merely writes it on both of its underlying streams.
Example 6.5. The TeeOutputStream Class
package com.macfaq.io;
import java.io.*;
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