Download Midterm Exam 2 - Spring 2005 | Object Oriented Programming I | CMSC 131 and more Exams Computer Science in PDF only on Docsity!
CMSC
Spring 2005
Midterm
First Name: _______________________
Last Name: _______________________
Student ID: _______________________
Section time (Circle One): 8AM 9AM 10AM 11AM 12PM 1PM
I pledge on my honor that I have not given or received any unauthorized assistance on this examination.
Your signature: _____________________________________________________________
General Rules (Read):
- This exam is closed-book and closed-notes.
- If you have a question, please raise your hand.
- Total point value is 100 points.
- WRITE NEATLY. If we cannot understand your answer, we will not grade it (i.e., 0 credit).
Grader Use Only:
#1 (40) #2 (15) #3 (30) #4 (15)
Total (100)
Problem 1 General Questions (40 pts)
a. (3 pts) Which of the following Java constructs can be used to control the program execution in an iteration statement? Circle your choice(s).
i. break
ii. continue
iii. static
b. (3 pts) Math.random() generates a double value greater than or equal to 0 and less than 1. Define an expression that generates a random value greater than or equal to 10 and less than
c. (4 pts) Answer the questions below based on the following prototypes:
int raise(float x); // prototype 1
int raise(String x); // prototype 2
float raise(float x); // prototype 3
int lower(float x); // prototype 4
i. Do the methods represented by prototypes 1 and 2 overload each other? Yes/No ii. Do the methods represented by prototypes 1 and 3 overload each other? Yes/No iii. Do the methods represented by prototypes 2 and 3 overload each other? Yes/No iv. Do the methods represented by prototypes 1 and 4 overload each other? Yes/No
d. (2 pts) Can you declare a formal parameter with the same name as a local variable? Yes/No
e. (2 pts) Can constructors be overloaded? Yes/No.
k. (8 pts) Rewrite the following cascaded if statement into a switch statement (t and x are integer variables).
if (t = = 3) x = 30; else if (t == 4) x = 10; else if (t == 2 || t = = 7 || t = = 8) x = 20; else x = 100;
Write the switch statement here.
l. (5 pts) Based on the following two declarations indicate whether the expressions below are valid or invalid?
String b = "Hello"; char[] c = {'H', 'e', 'l', 'l', 'o'};
System.out.println(b[2]); // VALID / INVALID
System.out.println(b.length); // VALID / INVALID
System.out.println(c.length()); // VALID / INVALID
System.out.println(c.charAt(1)); // VALID / INVALID
System.out.println(String.valueOf(c)); // VALID / INVALID
Problem 3 Class Implementation (30 pts)
A catering program uses a class named “Party” to keep track of information about a party. The class has the following two private instance variables:
private String name; // Represents the name of the party private double cost; // Represents the cost of the party in dollars
Define the following Party class methods (you don’t to have to define the class). All the methods are non- static unless otherwise specified.
- Constructor – Takes a String reference and a double as parameters. The current object is initialized with a copy of the parameters’ values.
- Copy Constructor – Define the appropriate copy constructor for this class. This method produces a new object containing a copy of the original object’s instance variables.
- different – Takes a Party object reference as a parameter. It returns true if the current object and the parameter represent different parties and false otherwise. Two parties are considered different if they have different names. This method is case sensitive, i.e., “a” and “A” are considered different.
- merge – Static method that takes two Party object references as parameters. The method returns a new object that represents the merging of two parties. The new object will have as its name the concatenation of the parameters’ names, the first parameter followed by the second parameter, separated by a “/”. The cost of the new object will be the sum of the parties’ costs.
- merge – Non-static method that takes as parameter a Party object reference. The method returns a new object that represents the merging of the current object and the parameter, in that order. You must implement this method using the static merge method previously described. The current object may not be modified.
- incrementCost – This method takes a double as a parameter. The method increases the cost of the current object by the parameter value and returns a reference to the current object. The current object is modified. No new object is created.
Start writing the methods on this page and continue on the next page.
Page for Party methods
