Marks this thread as either a {@linkplain #isDaemon daemon} thread
or a user thread. The Java Virtual Machine exits when the only
threads running are all daemon threads.
<p> This method must be invoked before the thread is started.
@param on
if {@code true}, marks this thread as a daemon thread
@throws IllegalThreadStateException
if this thread is {@linkplain #isAlive alive}
@throws SecurityException
if {@link #checkAccess} determines that the current
thread cannot modify this thread
Marks this thread as either a {@linkplain #isDaemon daemon} thread or a user thread. The Java Virtual Machine exits when the only threads running are all daemon threads.
<p> This method must be invoked before the thread is started.
@param on if {@code true}, marks this thread as a daemon thread
@throws IllegalThreadStateException if this thread is {@linkplain #isAlive alive}
@throws SecurityException if {@link #checkAccess} determines that the current thread cannot modify this thread