330 Java Tips.pdf - FTP Server

Operational Systems & Java
during the shutdown sequence, as will non-daemon threads if shutdown was initiated
by invoking the exit method. Once the shutdown sequence has begun it can be
stopped only by invoking the halt method, which forcibly terminates the virtual
machine.
Once the shutdown sequence has begun it is impossible to register a new shutdown
hook or de-register a previously-registered hook. Attempting either of these
operations will cause an IllegalStateException to be thrown.
Shutdown hooks should also finish their work quickly. When a program invokes exit
the expectation is that the virtual machine will promptly shut down and exit. When the
virtual machine is terminated due to user logoff or system shutdown the underlying
operating system may only allow a fixed amount of time in which to shut down and
exit. It is therefore inadvisable to attempt any user interaction or to perform a
long-running computation in a shutdown hook."
more read here: http://java.sun.com/j2se/1.3/docs/api/index.html
Q: Is it possible for a minimized window in MS Windows task bar to start
blinking? In any IRC client a minimized window starts blinking when a new message
appears in it. Is it possible in Java?
Answer: I doubt very much that it is possible with pure java; you would have to use
some native code to achieve that. Maybe what you could try though, is to play
around with the icon used in the title bar of the frame. I haven't tried this myself - and
in any case I'm running linux, but it might be possible to have two icons and to switch
them around at some rate using the Frame.setIconImage(Image) method. This will
only affect the icon itself - not the whole window, but it's better than nothing.
--
Allen Wallis
Q: How do I find the list of all system properties?
Answer: do smth like this:
Enumeration list = System.getProperties().propertyNames();
while(list.hasMoreElements()){
System.out.println((String) list.nextElement());
}
}
Is it cls-like command in DOS (CMD) window? I would like to clean the screen the
user sees?
Answer: Unfortunately there is no command as "cls", but try this instead:
for (int i=0; i