CMSC 131 Summer 2005 Quiz 3 Worksheet
The third Quiz of the course will be on Friday June 24. The following list provides more
information about the quiz:
•You will have 15 minutes to complete the quiz.
•It will be a written quiz (not using any computer).
•It will be closed-book, closed-notes, and no calculator is allowed.
•Answers must be neat and legible. We recommend that you use pencil and eraser.
•The quiz will be based on the exercises you will find below.
The following exercises cover the Quiz#3 material. Solutions to these exercises will not
be provided, but you are welcome to discuss your solutions with TAs and instructors
during office hours.
Problem 1 (General Questions)
a. What is the difference between System.out.println and System.out.print ?
b. What is the heap?
c. What is the difference between an object and a class?
d. Is the heap an infinite memory area? Explain.
e. What is garbage collection?
f. Are the following assignments valid?
int age = 17;
double temp = 3.4;
String m = “John” + age + “/” + temp;
g. What is a reference variable?
h. What is the difference between a reference and a primitive variable?
i. How many reference variables can be associated with an object?
j. In the following code fragment, how many objects do we have at every step?
String r;
String s; // Step 1
r = s = “Happy”; // Step2
r = new String(s); // Step 3
r = null; // Step 4
r = new String(“John”); // Step 5
k. When do we use the String equals method?
l. What would happen when you execute the following code fragment?
String k = null;
System.out.println(k);
System.out.println(k.length());
