What is output to the screen by the following code?

System.out.println("Sum=" + 4 + 5); 

Sum= 5 4

Sum=45

Sum=9

Sum=54

Sum= 4 5

What is output to the screen by the following code?

System.out.print(21/5);

4

5.5

5

3.5

4.2

Consider the following three classes: Clothing, Socks, and Sweater. Which would you choose be an abstract class?

All of the items listed.

Socks

Sweater

Socks and Sweater

Clothing

Which of the following keywords allows a child class to access the overridden methods in a parent class?

super

extends

this

None of the answers listed.

new

Questions 9 and 10 refer to the following code:

public abstract class Phone { abstract void dial(); } public class MobilePhone extends Phone { } public class RotaryPhone extends Phone { public void dial () { //code not shown } } 

Which of the following statements is true?

Neither can be instantiated since they do not include constructors.

Neither can be instantiated since you cannot extend an abstract class.

MobilePhone can be instantiated.

RotaryPhone cannot be instantiated.

RotaryPhone can be instantiated.

Which of the following statements is true?

A Phone object can access methods in MobilePhone.

A RotaryPhone object can access methods in MobilePhone.

RotaryPhone inherits from Phone and MobilePhone.

RotaryPhone inherits from Phone.

None of the answers listed.

Suppose a class implements the Comparable interface. Which of the following methods must the class include?

charAt

substring

compareTo

length

indexOf

Questions 12-14 refer to the following:

public class A { public A () { System.out.print(one ); } public A (int z) { System.out.print(two ); } public void doStuff() { System.out.print(six ); } } public class B extends A { public B () { super (); System.out.print(three ); } public B (int val) { super (val); System.out.print(four ); } } 

What is printed when the following line of code is executed?

B b = new B();

three two

one three

four two

two four

one four

What is printed when the following line of code is executed?

A a = new B(5);

two

four

one

four one

two four

Assume that variable b has been instantiated as a B object. What is printed when the following line of code is executed?

b.doStuff();

two

five

four

three

six

Which of the following is true about interfaces:

An interface can have only non abstract methods.

All methods in an interface must be abstract.

A class can only implement one interface.

None of the items listed.

Can not contain constants but can have variables.

What is the rule for a super reference in a constructor?

It must be in the parent class' constructor.

You cannot use super in a constructor.

It must be the last line of the constructor in the child class.

Only one child class can use it.

It must be the first line of the constructor in the child class.

Consider the following class definition.

public class WhatsIt { private int length; private int width; public int getArea () { // implementation not shown } private int getPerimeter () { // implementation not shown } } 

A child class Thingy that extends WhatsIt would have access to:

width, length, getPerimeter()

getPerimeter()

All of the items listed.

getArea()

width, length, getArea()

Questions 18 - 20 pertain to the following class, Point:

public class Point { private double x; private double y; public Point() { this (0, 0); } public Point(double a, double b) { /* missing code */ } // ... other methods not shown } 

Which of the following correctly implements the equals method?

public boolean equals(Point p) { return (x == p.x && y == p.y ); } 

public void equals(Point p) { System.out.println(x == p.x && y == p.y); } 

public void equals(Point p) { return (x == p.x && y == p.y ); } 

public boolean equals(Point p) { return (x == Point.x && y == Point.y); } 

public boolean equals(Point p) { System.out.println(x == p.x && y == p.y); } 

The default constructor sets x and y to (0, 0) by calling the second constructor. What could be used to replace /* missing code */ so that this works as intended?

a = 0; b = 0;

this (x, y);

this(0, 0);

x = a; y = b;

a = x; b = y; 

Which of the following correctly implements a mutator method for Point?

public double getX() { return x; } 

public void setCoordinates (double a, double b) { x = a; y = b; } 

None of the items listed.

public double getX() { return a; } 

public void setCoordinates (double a, double b) { Point p = new Point(a,b); }