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Midterm Exam 1 Questions - Object Oriented Program I - Spring 2005 | CMSC 131, Exams of Computer Science

University of Maryland Computer Science

Material Type: Exam; Class: OBJECT-ORIENTED PROG I; Subject: Computer Science; University: University of Maryland; Term: Spring 2005;

Typology: Exams

2019/2020

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CMSC131

Spring 2005

Midterm #1

First Name: _______________________

Last Name: _______________________

Student ID: _______________________

Section time ___________ TAs: __________________________

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:

(40)

(15)

(30)

Total

(100)

Discover Exams of Computer Science University of Maryland

Partial preview of the text

Download Midterm Exam 1 Questions - Object Oriented Program I - Spring 2005 | CMSC 131 and more Exams Computer Science in PDF only on Docsity!

CMSC

Spring 2005

Midterm

First Name: _______________________

Last Name: _______________________

Student ID: _______________________

Section time _ TAs: ________________

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:

Total (100)

Problem 1 General Questions (40 pts)

a. (4 pts) Which of the following are valid Java identifiers? (Circle the valid ones.)

Sugar wall&8 U_k 3Abc

b. (2 pts) Is null the same as the empty string ("")? Yes/No (Circle one.)

c. (2 pts) Can two or more reference variables refer to the same object at the same time?

Yes/No (Circle one)

d. (2 pts) How many distinct String object instances are created in the following code segment?

String value = "Baseball"; value = "GoodBye";

String valueTwo = value; Answer:_______

e. (2 pts) The following code fragment does not compile. Why? Briefly explain (in one or two

sentences).

String k; System.out.println(k.length());

Answer:

f. (3 pts) What is the output generated by the following code segment?

int y = 20; int x = 40; double d = 30.5; if (x > 5 && d < 30 && (++y > 5)) { x++; } System.out.println("X: " + x); System.out.println("Y: " + y); System.out.println("D: " + d);

_______________________________________

h. (2 pts) What is the relationship between a class and an object? Do both terms refer to the

same entity? Briefly explain (in one or two sentences).

Answer:

i. (2 pts) Write the file name extension associated with a file containing bytecode.

j. (6 pts) Add parentheses to specify completely the order in which the following expressions

will be evaluated. You do not need to specify the final value of the expressions. The

variables associated with the expressions are:

int w = 10, x = 20, y = 30; boolean b;

i. b = w < x && y < 30 ;

ii. x = w *= y ++ - 2 ;

iii. y = - x + - y * 5 % 3 ;

k. (3 pts) Which of the following statements are valid?

i. long x = 20; VALID/INVALID

int y = x;

ii. float m = 20.50f; VALID/INVALID

double k = m;

iii. long m = 5L * 4; VALID/INVALID

Note : Add parentheses only.

DO NOT evaluate.

l. (2 pts) What will occur if the following code segment is executed? Briefly explain (in one or

two sentences).

String music = null; boolean b = music.equals(null);

Answer:

m. (4 pts) Complete the following trace table.

int a = 10, b = 21; int c = b % 2; b += a; a *= 2; boolean d = true && !(a > 10);

a b c d

Problem 3 Pseudocode (15 pts)

Write pseudocode (NO IMPLEMENTATION) for a method that reads a sequence of user-provided

integer values and returns the minimum value in the sequence. The method has one formal

parameter, an integer called size , that specifies the size of the sequence. You may assume that size

is a valid integer value (> 0). You should return the first minimum value if there is more than one.

As a simplification, you may read a value and store it in some variable x as follows: x = read().

Also you may print a value x or a message as follows: print(x) or print(“Hello”).

Important: Keep in mind that pseudocode is not an English prose-like description of a particular

task. (You will receive 0 credit if you provide a text paragraph that describes the task.) Rather, it is

a code-like step-by-step procedure that describes how to accomplish the given task. Your

pseudocode should be detailed enough that it can be converted by a competent programmer into

Java, but should not contain Java-specific details.

WRITE YOUR PSEUDOCODE IN THE SPACE BELOW.

Problem 4 Class Implementation (30 pts)

For this problem you will implement a class called Utilities. The class has two non-static public

methods.

a. minimum - It is the implementation of the pseudocode you defined above. Use the

message “Enter Value” to prompt the user for values. Each input value will be read

using a separate call to JOptionPane. You may assume that all inputs are valid.

Midterm Exam 1 Questions - Object Oriented Program I - Spring 2005 | CMSC 131, Exams of Computer Science

Related documents

Partial preview of the text

Download Midterm Exam 1 Questions - Object Oriented Program I - Spring 2005 | CMSC 131 and more Exams Computer Science in PDF only on Docsity!

CMSC

Spring 2005

Midterm

First Name: _______________________

Last Name: _______________________

Student ID: _______________________

Section time ___________ TAs: __________________________

I pledge on my honor that I have not given or received any unauthorized assistance on this

examination.

Your signature: _____________________________________________________________

General Rules (Read):

credit).

Grader Use Only:

Total (100)

Problem 1 General Questions (40 pts)

a. (4 pts) Which of the following are valid Java identifiers? (Circle the valid ones.)

b. (2 pts) Is null the same as the empty string ("")? Yes/No (Circle one.)

c. (2 pts) Can two or more reference variables refer to the same object at the same time?

Yes/No (Circle one)

d. (2 pts) How many distinct String object instances are created in the following code segment?

String valueTwo = value; Answer:_______

e. (2 pts) The following code fragment does not compile. Why? Briefly explain (in one or two

sentences).

Answer:

f. (3 pts) What is the output generated by the following code segment?

_______________________________________

_______________________________________

_______________________________________

h. (2 pts) What is the relationship between a class and an object? Do both terms refer to the

same entity? Briefly explain (in one or two sentences).

Answer:

i. (2 pts) Write the file name extension associated with a file containing bytecode.

j. (6 pts) Add parentheses to specify completely the order in which the following expressions

will be evaluated. You do not need to specify the final value of the expressions. The

variables associated with the expressions are:

i. b = w < x && y < 30 ;

ii. x = w *= y ++ - 2 ;

iii. y = - x + - y * 5 % 3 ;

k. (3 pts) Which of the following statements are valid?

i. long x = 20; VALID/INVALID

ii. float m = 20.50f; VALID/INVALID

double k = m;

iii. long m = 5L * 4; VALID/INVALID

Note : Add parentheses only.

DO NOT evaluate.

l. (2 pts) What will occur if the following code segment is executed? Briefly explain (in one or

two sentences).

Answer:

m. (4 pts) Complete the following trace table.

a b c d

Problem 3 Pseudocode (15 pts)

Write pseudocode (NO IMPLEMENTATION) for a method that reads a sequence of user-provided

integer values and returns the minimum value in the sequence. The method has one formal

parameter, an integer called size , that specifies the size of the sequence. You may assume that size

is a valid integer value (> 0). You should return the first minimum value if there is more than one.

As a simplification, you may read a value and store it in some variable x as follows: x = read().

Also you may print a value x or a message as follows: print(x) or print(“Hello”).

Important: Keep in mind that pseudocode is not an English prose-like description of a particular

task. (You will receive 0 credit if you provide a text paragraph that describes the task.) Rather, it is

a code-like step-by-step procedure that describes how to accomplish the given task. Your

pseudocode should be detailed enough that it can be converted by a competent programmer into

Java, but should not contain Java-specific details.

WRITE YOUR PSEUDOCODE IN THE SPACE BELOW.

Problem 4 Class Implementation (30 pts)

For this problem you will implement a class called Utilities. The class has two non-static public

methods.

a. minimum - It is the implementation of the pseudocode you defined above. Use the

message “Enter Value” to prompt the user for values. Each input value will be read

b. components – The method’s prototype is:

public Picture components(Picture picture, String colors);

This method is basically the one you implement in homework #3. It will return a Picture

with only the color components specified in the colors parameter. The colors parameter

can be any combination of the lowercase letters r, g, and b. If you don’t recall how to use

the selectComponents class then read the description at the end of the page.

Remember that to retrieve a character from a String we use the method charAt(x)

where x is an integer index value. The following are examples of some valid values for

Section time _ TAs: ________________