PTC Intern interview questions

Introduce Yourself. Polymorphism. Difference Between ArrayList and List. One Coding Question basedon an array . Another coding question was based on Questions were asked based on projects. It took a Little Time. Some queries were asked related to my project and of course DBMS queries because it is a core subject. Difference Between Set and List in terms of java. There is ABC Corporation. It has 200 shares and Per Share cost 50rs. Suddenly 50% of increment is gained and later on 40% of fall of Share. What would be the gain and losses? Queue data structure. LILO ?? What is it?