Causes the first selection operation that has not yet returned to return immediately.
If another thread is currently blocked in an invocation of the {@link #select()} or {@link #select(long)} methods then that invocationwill return immediately. If no selection operation is currently in progress then the next invocation of one of these methods will return immediately unless the {@link #selectNow()} method is invoked in themeantime. In any case the value returned by that invocation may be non-zero. Subsequent invocations of the {@link #select()} or {@link #select(long)} methods will block as usual unless this method is invokedagain in the meantime.
Invoking this method more than once between two successive selection operations has the same effect as invoking it just once.
@return This selector