Write a class that implements a parallel quick sort for an array of integers in Java. Partition the array into four partitions and create four threads to sort the partitions in parallel. Each thread must sort only one of the four original partitions.

Create a class that extends Thread to implement your thread. Only create ONE thread class. Do not create a separate thread class for each thread.

After the four threads are started, the main program must wait (join) until all threads are done. The main program must then verify that the array is properly sorted.