Parallel array sorting in Java 8

In Java 8, there are new methods introduced in java.util.Arrays class for Parallel Sorting.

In parallel array sorting the sorting algorithm is a parallel sort-merge that breaks the array into sub-arrays that are themselves sorted and then merged. The Fork/Join common thread pool is used to execute any parallel tasks. The Fork/Join pool introduced in Java 7.

Parallel array sorting a simple example:

Output :

Parallel array sorting time test:


From the above example output you can observe that, when array size small sequential array sort performs better, but when array size is very large then parallel array sort perform tremendously better.

Parallel array range sort example:

Arrays.parallelSort method sorts the specified range of the specified array of objects into ascending order, according to the natural ordering of its elements.

The range to be sorted you have to provide fromIndex and toIndex to the Arrays.parallelSort method.

If fromIndex and toIndex is same then you will get empty results.

fromIndex is inclusive and toIndex is exclusive.

The range should be in between zero and length of array.