JAVA TEST 2

6. System, String, StringBuffer,

Math, and Wrapper Classes

Most of the Date class methods have been

deprecated. Which of the following methods is one

of those that have been deprecated? 不推荐

*B. getDate()

Which line of code will create a new string in the

string pool that can be referenced by the identifier

myGame?

*A. String myGame = "basketball";

Which lines of code produce the following output?

Hello

How are you?

*D. System.out.println("Hello");

System.out.println("How are you?");

Which package(s) are usually imported when using

dates in a program?

*D. java.util.* and java.text.*

the screen.

Which type of data does the System.in.read()

method read?

*C. It reads in a byte at a time and returns an integer in

the range of 0 to 255.

What must be imported to use

System.out.println()?

*D. nothing

What is printed out to the screen when the code in

the listing provided is executed?

*B. The answer is 2.345

What happens if you try to use the following code?

Double num1 = new Double(1.23);

double num2 = num1.doubleValue();

*D. It will compile and num2 will have the value of 1.23.

Which would be the best StringBuffer method to

use to change the StringBuffer object containing

"bob saw mom" to a StringBuffer object containing

"mom was bob"?

*D. reverse()

What must you do when using a primitive data

method?

*C. Primitive data does not have methods.

What is the value of s2 after this code executes?

String s1 = "Happy day";

String s2 = s1.substring(1,5);

*C. "appy"

If you are writing a piece of code that needs to

determine whether the user entered 'q' to quit, not

knowing if they would use upper or lowercase,

which method(s) would you use? The user's

response is held in the char variable choice .

*D. Character.toUpperCase(), and the comparison operator,

==

What happens if you use the compareTo() method

and send an object that is not a String as a

parameter?

*B. The compareTo() method will throw an exception.

Which of the following is true about the Console

class used in this and subsequent chapters?

*B. It is a class written for us to use in this course to

simplify input and output operations.

Which of the following is a true statement about

the toString() method of the StringBuffer class?

*B. It converts the data in the StringBuffer to a String and

returns that new String.

Which method can you call to obtain the integer

version of a String?

*A. Integer.parseInt()

Where can you find the documentation for the

java.math package?

*A. Sun Java documentation

7. Arrays

What is the index of the last element in an array?

*D. The size of the array minus one.

What happens when an array of objects is created?

*A. The array contains locations for references to objects

of the specified type.

What is the proper syntax for accessing the fifth

element of an array?

*D. theArray [4]

What is contained in each element of the array

when the following statements are executed?

int numbers [];

numbers = new numbers [2];

*B. 0

How many elements are in dblArray?

*B. 7

What is the output of the displayed code?

*D. 4.0, 8.0, 12.0, 16.0, 20.0, 24.0,

Which class actually contains the line that prints

the artist to the screen?

*C. The artist is printed from the Song class.

Which string is listed on the screen first?

*B. The song on track

What is the order of the array in the graphic after it

has been sorted in ascending order?

*A. 1, 2, 3, 6

What is the output of the program in the graphic?

*E. 20

Which of the following statements correctly

defines the term "array?"

*A. A variable reference to a java object that can access a

sequence of contiguous storage locations storing the same

type of data.

What is the correct syntax for declaring an array?

*B. int[] quantity;

Which of the following lines of code displays the

correct syntax for initializing an array with default

values?

*A. int[ ] quantity = {4, 5, 6, 78,100};

If a code references an element of an array for

which there is no index, what type of exception is

generated?

*D. IndexOutOfBoundsException

What is the most efficient way to store and

randomly access a sequence of objects that Java

provides?

*D. Array

Where is the array and the objects that each

element references stored?

*C. Heap

What does the following line of code do?

quantity = new int[3];

*B. Creates storage for three int.

What is combined with the name of the array

variable to provide a reference to a single element

of the array?

*C. Index value

Which term is used for storing values in an array?

*D. Populating

When programmers need to initialize a large

number of variables with a calculated value, what

should they create?

*B. StudentsInTheClass[1]=new student (456778998,

"Peter Lei")

When primitive data is stored on the heap, it is

initialized with what value?

*C. Default value of the data-type

In order for a static method to access any

non-static methods of a class, what must it

contain?

*B. Object instance

When the values of each element in one array

correspond to the meaning of the values in a

second array, what are the arrays known as?

*A. Parallel arrays

What is a requirement for the creation and

initialization of multidimensional arrays?

*D. Each dimension must be created before it can initialize

values for the next dimension.

What is the output of the Java code?

*B. The element at 1 is 4.

The element at 2 is 2.

The element at 3 is 5.

The element at 4 is 3.

8. Classes and Inheritance

The phrase "a method that converts a reference

value of an object to a string" correctly defines

which of the following methods?

*C. toString()

Which of the following can be used as an abstract

representation of behaviors?

*B. super class

The phrase "The super class for all classes" refers

to which class?

*B. Object

Which keyword is used to make a class definition

include the non-private attributes and behaviors of

a parent class, as well as additional attributes and

behaviors that are specific to the class being defined?

*A. extends

Which term refers to the process of redefining or

customizing the definition of a parent class

method?

*B. overriding

Which of the following statements is incorrect?

*C. Class fourWDTruck inherits from class Truck so Truck

'is a' fourWDTruck

Which method is called by the garbage collector

before an object is destroyed?

*D. finalize()

Inheritance defines which type of relationships

among classes and objects?

*A. is-a

What can be used as an abstract representation of

common behaviors and data among objects?

*C. data member

In Java, a class can inherit from how many other

classes?

*A. one

What would be the best parent class for these

items: apple, orange, tomato, and kiwi?

*C. Fruit

What is the purpose of Dynamic Binding?

*B. It resolves what method to call when a method is

implemented by more than one class in the inheritance

hierarchy.

Which term refers to the path from a specific class

to its ancestors?

*B. inheritance hierarchy

Which of the following is incorrect?

*D. A class automatically extends class Object and can

extend any number of other classes.

Which term refers to the mechanism in the Java

language that adds enormous flexibility to your

programs?

*A. polymorphism

What is it called when methods have the same

name and can perform different tasks depending

on the subclass that calls the method?

*B. polymorphism

Which of the following statements is incorrect?

*B. The keyword 'super' functions the same as 'me.'

Which statement is correct?

*C. When a super class is an abstract representation, the

super class cannot be used as an object.

In general, your class design should include

overridden methods for which of the following?

*A. equals(), hashcode(), toString()

The phrase "a class from which no objects are

expected to be created" refers to which of the

following terms?

*A. abstract class

Which class would Person be considered, if

employee and Customer both inherit common

behaviors from the Person class?

*C. parent

Which of the following is incorrect?

*D. An abstract class generally provides all the

functionality needed for any class that inherits from it.

Which keyword is used to prevent a class from

being extended?

*D. final

Which access modifier must be applied to a method

when creating an interface?

*A. public

Which of the following statements is incorrect?

*D. An extended class definition includes all private

attributes and behaviors of the parent.

9. Understanding Packages

Which one of the AWT class categories can be used

to hold other components?

*B. Applet

Which of the following AWT classes is used to

position components in a container?

*A. FlowLayout

Which of the following utilities can be used to

combine all the files in a package into a single

compressed file?

*D. jar

What information does the PATH variable of an

Operating System contain?

*B. Program executable directories

GUI programs fall into which of the following

programming paradigms?

*C. event driven

Which of the following allows the management of

classes that are part of a collection?

*C. Packaging

Which of the following AWT classes can draw

graphics or manipulate images?

*B. Graphics

Which file extension will end a source code file or

compilation unit?

*C. .java

Which component can house other components?

*A. containers

Which of the following statements is used to locate

classes that are part of a package?

*D. import statement

Suppose you are an entry-level programmer

starting to layout a new application. Your

supervisor tells you to make sure you create your

java application using packages because packages are

easier to manage. Why would packages be easier to

manage?

*B. Because the program will be created as a collection of

classes.

Which of the following statements is true

concerning the use of packages?

*C. Minimizes name collision

Which of the following are identifiers of a class and

it's methods?

*B. Namespaces

Which of the following is the term used to identify

the hierachy of directories where a file is located?

*D. Path

What are the two variables that affect class files

and JDK programs?

*A. Path and Classpath

Packages are used to control the naming of classes.

For example, standard library math functions are in

the Math class, which is in the java.lang package.

Based on the information given, what is the complete

name of this class?

*C. java.lang.Math

Which utility is used to improve management and

delivery of classes?

*B. jar

10. Creating GUIs Using AWT

ContainerListener is an interface name for the

container category. This particular interface name

has methods associated with it. Which of the

following is a valid method associated with the

container category?

*D. componentAdded

What is true about the BorderLayout class?

*B. It divides the Container that uses it into five sections.

Which is a difference between the FlowLayout and

the BorderLayout?

*A. In FlowLayout the components may move from one

row to another when the panel is resized, but with a

BorderLayout the components stay within their region.

Which of the following lines of code would create a

Button object that has the label "Exit"?

*C. Button bt = new Button("Exit");

Which of the following lines of code will set the

layout of a Frame named fr to BorderLayout?

*C. fr.setLayout(new BorderLayout());

Which of the following is a region for a

BorderLayout?

*A. Center

What is one difference between a Window object

and a Panel object?

*A. A Window object does not need to be in another

Container, while a Panel object must.

What is the AWT?

*A. Abstract Windowing Toolkit

Which of the following is true about the Panel

class?

*B. Panel objects must be contained in another Container

object.

Creating a GUI involves many steps that have to be

considered with equal importance. According to

the chapter readings, how many steps are there in

the process?

*D. 8

The BorderLayout is the default layout for which

class of Components?

*C. Frame

Which of the following is true about layout

managers?

*B. Every container has a default layout manager.

In Java's event delegation model, which section

refers to the event object that encapsulates

information about the event?

*B. The event

What is the best way to handle the sizing of the

Components in a Container?

*B. Let the layout manager handle the sizing.

In Java's event delegation model, which section

refers to the object that can generate an event

object?

*C. the source of an event

What is the class that is used to set some

properties of components and graphics?

*A. FontMetrics

What are the maximum number of Components

you can place in a Container that uses the

BorderLayout?

*D. 5

What method of the Container class is used to put

Components in either a Window or a Panel object?

*C. add()

Which of the following is a true statement?

*D. The TextArea class and the TextField class are both

subclasses of the TextComponent class.

Which layout allows you to arrange Components

that are stacked on top of each other like a deck of

cards?

*A. CardLayout

John Smith has been hired to build a fully

functional java application with a GUI interface.

Which of the following components would likely

require the most code?

*A. Graphical User Interface (GUI)

Which lines of code would add a button to the top

region of an Applet using a BorderLayout? private

Button bt = new Button("At the top");

setLayout(new BorderLayout());

*C. add(bt, "North");

In Java's event delegation model, which section

refers to the object that can handle the event, the

event that is performing some task?

*A. The handler

What is the name of the abstract class that is an

ancestor class for all the objects that you see in a

GUI?

*D. Component

Which Component would you use to allow the user

to select one or more options?

*C. List