You can set it to anywhere in the range from MIN_PRIORITY to MAX_PRIORTY (static fields in the Thread class)

To set it from another thread, you can do the following:

Thrad t = new Thread(this);

t.setPriority(Thread.MIN_PRIORTY); // only eat idle time

t.start();

Or from your own thread:

// make it as real-time as possible

Thread.currentThread().setPriority(Thread.MAX_PRIORITY);