Optimized Bubble Sort in Java

Bubble sort is a simplest sorting algorithm which is used as a traditional method to introduce sorting concept to the students of computer science. Though it is not very efficient algorithm, it illustrates the sorting methodology very well.

Here is a bubble sort algorithm with "two optimizations" (think!!) :

Could you find out the optimizations used in above java code?
Best case running time for this algorithm in O(n) and worst case running time is O(n^2).