CS151 Take Home Midterm (3/8/01)

README

• You HAVE to print out all the answers as well as the output and source listings of the programming assignments. Please hand in both the printouts and a diskette containing your programs. The exam is collected in class on 3/13/01. If you are late in any way, 50% will be taken off in the first day, then 100% in the second day and after.
• If the instructor cannot show up on 3/13/01, the exam will be collected in the next lecture. This will only happen under extreme situation.
• DO NOT talk about the exam, COMPARE the exam, DISCUSS the exam, WORK WITH OTHER PEOPLE on the exam and CHEATING in any way you could think of. If two answers are found to be the same due to cheating. A F will be given for the course as a result and a letter might be sent to Dean of Students and the Computer Science Department. I do not want to do any of that, so LEARN the materials and DO IT YOURSELF.

MID TERM QUESTIONS

• The exam will total to 150 points.
• If you think the questions are not stated clearly in any way, WRITE down your assumptions and ask the questions. No email answer can be obtained from the instructor individually in order to be fair with all the students.
• Good Luck and have fun.

QUESTION 1

a. How many types of comments are in Java? What are they? (5 points)

b. Why use double instead of float in Java programming? (5 points)

c. Do all Java application have function(s)? (5 points)

d. What is the best way to find out the length of an array? (5 points)

QUESTION 2

a. What is the difference between Class and Object? (10 points)

b. Do you have to import a package for every Java program? Explain? (5 points)

c. Do you always need to create your own constructor for a class? (5 points)

QUESTION 3

a. There are only three access modifiers (public, private and protected) in Java. Right? (10 points)

b. Which class has more data and methods in general: superclass or subclass? (5 points)

c. What is protected keyword means in Java? (5 points)

QUESTION 4

a. Where is the applet runs on? (5 points)

b. How do you identify a program running on a computer in a network? (10 points)

c. If you are using Java code that throws exceptions, what do you do? (5 points)

QUESTION 5

a. Can you directly read from an URL object? (5 points)

b. What is a Socket? (10 points)

c. When creating a ServerSocket, why you do not need to provide a hostname? (5 points)

QUESTION 6 - Java Programming (50 points)

Write a Java application called URLMidterm that will

1. Present an UI (with swing) to the user and request
   • An URL address such as www.yahoo.com or www.ibm.com
   • An output file name
2. Create an URL object with http as protocol and the inputted address as resource name.
3. Parse the newly created URL object and print out in an output UI component such as text area in swing
   • protocol,
   • host,
   • filename,
   • port and
   • reference
4. Then, read directly from the URL object and print out all the contents from the input stream to the output file specified in step 1.
5. Run the program by "java URLMidterm"