JAVA - without using built in functions

Write a program to implement Quicksort. Also implement one of the slow sorts (Bubble, Insertion...). After you have tested both, generate a very large array (30,000 or more) of bytes and sort increasingly larger portions of the array (5000, 10000, ..., 30000) with both algorithms. Draw a graph of execution time versus number of elements for both algorithms. What are your conclusions?