What is the output? | Computer Science homework help

  

switch (val)

{

case 1:

System.out.print( “P” );

case 2:

case 3:

System.out.print( “Q” );

break;

case 4:

System.out.print( “R” );

default:

System.out.print( “S” );

}

What is the output?

A. 

PQS

B. 

PQ

C. 

S

D. 

P

4 points 

Question 2

How many times will “hello” be printed by the following:

for (int i = 0; i < 10; i++)

System.out.println(“hello”);

A. 

9

B. 

0

C. 

11

D. 

10

4 points 

Question 3

When writing a subclass, which of all of the following are true?

A. 

You can override methods of the superclass

B. 

You can inherit methods from the superclass

C. 

You can define new methods in the subclass

D. 

All of the above

4 points 

Question 4

Select the best answer.

Local variables are destroyed when

A. 

the constructor runs

B. 

you explicitly delete them

C. 

the object is no longer in use

D. 

the method ends

4 points 

Question 5

Which of the following is a valid constructor method header for a class named Car?

A. 

Public Class Car

B. 

public car(String model)

C. 

public class Car(String model)

D. 

public Car(String model)

4 points 

Question 6

For the code:

int m = 0;

while (m++ < 2)

System.out.print(m + ” “);

What is the output?

A. 

0 1 2

B. 

1 2

C. 

1

D. 

0 1

4 points 

Question 7

Remember that the % operator evaluates to the remainder after integer division e.g. 8 % 4 is 0, 11 % 4 is 3. What is the value of x after the following?

int x = 0;

for (int i = 1; i < 6; ++i)

if (i % 2 == 0)

x = x + i;

A. 

0

B. 

6

C. 

15

D. 

21

4 points 

Question 8

Select the best answer.

The main purpose of a constructor is to

A. 

Initialize instance variables

B. 

Name the method

C. 

Construct a method

D. 

Return a value

4 points 

Question 9

Given the following class definition:

public class Car

{

private double fuelLevel;

public Car(double gallons)

{

fuelLevel = gallons;

}

public void addGas(double gallons)

{

fuelLevel += gallons;

}

}

and this code segment:

Car car1 = new Car(20);

Car car2 = car1;

car2.addGas(10);

What is the value stored in fuelLevel for car1?

A. 

20.0

B. 

0.0

C. 

10.0

D. 

30.0

4 points 

Question 10

Assume that val has been declared as an int for the code below:

if (val >= 4)

System.out.println(“Test A”);

else if (val > 9)

System.out.println(“Test B”);

else

System.out. println(“Test C”);

Which one of the alternatives below will result in “Test C” being printed:

A. 

val is 4

B. 

no values of val will do this

C. 

val < 4

D. 

val between 4 and 9

4 points 

Question 11

Given 

int quantity = 3;

double value = 7.52;

String number = “one”; 

Which of all of the following are valid assignments?

A. 

quantity = value;

B. 

quantity = (int)value;

C. 

value = quantity;

D. 

quantity = (double)value;

E. 

quantity = number;

F. 

Both B and C

4 points 

Question 12

Select the best answer.

A(n) ____ can add instance variables and methods to an existing class.

A. 

subclass

B. 

polymorphism

C. 

superclass

D. 

constructor

4 points 

Question 13

What is the error in the following code fragment?

double data[] = new double[20]; 

data[20] = 15.25;

A. 

Out-of-bounds error

B. 

Data not initialized

C. 

A two-dimensional array is required

D. 

A cast is required

4 points 

Question 14

If you know that your loop must iterate at least one time, it is recommended that you use a _________ loop 

A. 

do _ while

B. 

repeat

C. 

for

D. 

while

4 points 

Question 15

Multiplying an int (such as 5) by a double (such as 0.1) gives

A. 

an exception is thrown

B. 

an int

C. 

an error

D. 

a double

4 points 

Question 16

After executing this code segment:

double v1 = 2000.0;

double v2 = v1;

v2 = v2 + 500.0;

What will be the value of v1 ?

A. 

Unknown

B. 

2000.0

C. 

2500.0

D. 

0.0

4 points 

Question 17

Which of the following indicates that a method does not return a value?

A. 

double

B. 

static

C. 

void

D. 

public

4 points 

Question 18

Where an inherited method is overridden, the type of the actual object, not the type of the reference to the object is used to determine which method to call?

True

False

4 points 

Question 19

The compiler will generate an error if the same name but different signature is used for more than one method or constructor.

True

False

4 points 

Question 20

Given this code fragment: 

{

int x = 5, y = 6, z = 7;

foo(x, y, z);

System.out.println(x + “, ” + y + “, ” + z);

}

public void foo(int a, int b, int c)

{

a = a + 3;

b = a + c;

c = c + b;

}

What is the output?

A. 

5, 6, 7

B. 

8, 12, 13

C. 

2, 0, 4

D. 

8, 15, 22

4 points 

Question 21

javadoc comments begin and end with:

A. 

// and //

B. 

/* and */

C. 

/** and */

D. 

/@ and @/

4 points 

Question 22

When using the BlueJ debugger, a class must be compiled before you can set a break point in it?

True

False

4 points 

Question 23

Which of the following are Java naming conventions?

#1: Classes start with an uppercase letter

#2: Methods start with an uppercase letter

#3: Object start with a lowercase letter

#4: Objects start with an uppercase letter

#5: Classes start with a lowercase letter

#6: Methods start with a lowercase letter

A. 

#1, #3 and #6

B. 

#4, #5 and #6

C. 

#1, #2 and #4

D. 

#3, #5 and #6

4 points 

Question 24

Given the array

double cost[] = new double[5];

How would you access the last element of the array?

A. 

cost.get(4)

B. 

cost[4]

C. 

cost.get[5]

D. 

cost[5]

4 points 

Question 25

In a program, you create an object of a class using the keyword ____ .

A. 

abstract

B. 

extends

C. 

create

D. 

new

4 points 

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