Self-Check Problems 2. What is an object? How is an object difference from a class? 8. What is the difference between an accessor and a mutator? What naming conventions are used with accessors and mutators? 15. (You must complete Self-Check Problem 7 before answering this question) Write a toString method for the Name class that returns a String such as "John Q. Public". 20. What is the meaning of the keyword this? Describe three ways that the keyword can be used. 23. What is the difference between the public and private keywords? What items should be declared private? 29. What is cohesion? How can you tell whether a class is cohesive? 31. Add accessor methods to the Stock class to return the stock's symbol, total shares, and total cost