Download Problems with Solutions for Midterm Exam 1 - Object Oriented Program 1 | CMSC 131 and more Exams Computer Science in PDF only on Docsity!
CMSC
Fall 2004
Midterm
First Name: _______________________ Last Name: _______________________ Student ID: _______________________ Section time (10am/11am) ___________ TAs: __________________________ I pledge on my honor that I have not given or received any unauthorized assistance on this examination. Your signature: _____________________________________________________________ General Rules: This exam is closed-book and closed-notes. Write your answers in the space provided. If you need additional space, raise your hand. If you have a question, please raise your hand. Total point value is 100 points. Point values attached to individual problems are subject to possible (minor) changes. Good luck! Grader Use Only: #1 (35) #2 (20) #3 (20) #4 (25) Total (100)
Problem 1 (35 pts) a. (4 pts) Which of the following are valid Java identifiers? (Circle the valid ones.) Car $chultzie per%cent _22Skidoo b. (2 pts) Are the following two identifiers considered the same? Yes / No. (Circle one) temperature TEMPERATURE c. (2 pts) What value is assigned to a reference variable to indicate that it refers to NO object? (Circle one.) i. null ii. 0 (zero) iii. "" (empty string) iv. JOptionPane.NO_OBJECT d. (2 pts) How many distinct String object instances are created in the following code segment? String s1 = new String("Hello"); String s2 = "GoodBye"; Answer:_______ String s3 = s1; e. (2 pts) (Fill in the blank) The special area of memory where object instances are created and stored is called the ______________________________________ f. (5 pts) Which of the following are NOT Java primitive types? (Select all that apply.) i. integer ii. exponential iii. int iv. Float v. String g. (2 pts) As described in lecture, the software development lifecycle has five phases (parts). Name ANY TWO of them. (You do not need to describe them.)
h. (4 pts) Give a single Java statement (using System.out.println ) that outputs the following line: Bob said, "It's C:\WINDOW"
Problem 2 (20 pts) Show the output produced by each of the following program segments. ( Be careful. We have hidden some traps!) a. (10 pts) int x = 1; int y = 1; int w = 10; int s = 21; if( (x == 1) || ( y++ > 1) ) x++; System.out.println(x); System.out.println(y); System.out.println(w += 2); System.out.println(s % 10); if (s > 30 && true) if (s / 2 > 10) System.out.println("One"); else System.out.println("Two"); System.out.println("Three"); b. (10 pts) int x = 7; while (x > 0) { System.out.println(x); x -= 2; } System.out.println(x);
Problem 3 (20 pts) For each of the following parts, give a code fragment to achieve the given task. In each case we have given variable declarations, but we have intentionally not given the values of the variables. You may declare additional variables if needed. a. (5 pts) You are given three variables x , y , z , declared as shown below. Give a code fragment that does the following. If x is negative (less than 0), it assigns z to be the sum of x and y. Otherwise, it assigns z to be the maximum of x and y. You may not use any methods from the Java class library long x = ...; int y = ...; double z; / Write your code fragment below / b. (5 pts) You are given two variables d and e below, each of type int , and the third variable b of type boolean. Give a code fragment that sets b to true if d and e are both even or both odd, and sets b to false otherwise. int d = ...; int e = ...; boolean b; / Write your code fragment below /
Problem 4 (25 pts) Write a complete Java program that computes the numeric average of a set of scores. Your program will read the number (as an integer) of scores to process, followed by the actual scores (as doubles), and will print the numeric average of these scores. For example, if we wanted to compute the numeric average of 50.5 49.5 40.0 60. we would first input the value 4 (number of scores), then input each of the scores. The output of the program is a message that uses the following format: Average: numericAverage where numericAverage denotes the computed average. For the above example the output would be: Average: 50. The following specifications apply to this problem: Use the prompt string “ Enter Number ” to read the number of scores. Use the prompt string “ Enter Value ” to read each score value. Use JOptionPane method for input and output operations. Each number will be read using a separate call to JOptionPane. The name of the class will be ComputeAvg. You may assume that all inputs are valid , and the number of scores is 1 or greater. Meaningful variable names are NOT required. Try to maintain good indentation. . WRITE YOUR PROGRAM ON THE NEXT PAGE.
