Declarations and Access Control

Question 2

Identifiers can begin with what characters?

Answer 2

A letter, an underscore, or a currency character.

Question 3

After the first character, identifiers can also include…?

Answer 3

digits.

Question 4

How long can identifiers be made?

Answer 4

Any length.

Question 5

JavaBeans methods must be named using what kind of format?

Answer 5

camelCase

Question 6

Depending on the method’s purpose, JavaBeans methods must start with what?

Answer 6

set, get, is, add, or remove

Question 7

A ________ code file can have only one public class.

Answer 7

source

Question 8

(True/False) If the source file contains a public class, the filename cannot match the public class name.

Answer 8

false (it must match)

Question 9

A file can have only one _______ statement, but multiple imports.

Answer 9

package

Question 10

The package statement (if any) must be the ________ (non-comment) line in a source file.

Answer 10

first

Question 11

The ________ statements (if any) must come after the package and before the class declaration.

Answer 11

import

Question 12

If there is no package statement, what type of statements must be the first (non-comment) statements in the source file?

Answer 12

import

Question 13

(True/False) Package and import statements apply to some of the classes in the file?

Answer 13

false (applies to all the classes)

Question 14

Can a file have more than one nonpublic class?

Answer 14

yes

Question 15

Do files with no public classes have naming restrictions?

Answer 15

no

Question 16

What are the three access modifiers?

Answer 16

public, protected, and private

Question 17

What are the four levels of access?

Answer 17

public, protected, default, and private

Question 18

Classes can have only public or ______ access.

Answer 18

default

Question 19

(True/False) A class with default access can be seen only by classes within the same package.

Answer 19

true

Question 20

A class with ______ _______ can be seen by all classes from all packages.

Answer 20

public access

Question 21

Class visibility revolves around whether code in one class can ____an instance of another class, _____ another class, and ____methods and variables of another class.

Answer 21

create, extend or subclass, access

Question 22

Classes can also be modified with ______, abstract, or ________.

Answer 22

final…strictfp

Question 23

Can a class be both final and abstract?

Answer 23

no

Question 24

What type of class cannot be subclassed?

Answer 24

final

Question 25

What type of class cannot be instantiated?

Answer 25

abstract

Question 26

A single abstract method in a class means the _______ class must be abstract.

Answer 26

whole

Question 27

An _______ class can have both abstract and nonabstract methods.

Answer 27

abstract

Question 28

The first ________ class to extend an abstract class must implement all of its abstract methods.

Answer 28

concrete

Question 29

____________ are contracts for what a class can do, but they say nothing about the way in which the class must do it.

Answer 29

interfaces

Question 30

Interfaces can be implemented by any class, from any __________ ________.

Answer 30

inheritance tree

Question 31

Are interfaces like 100-percent abstract class, and are implicitly abstract whether you type the abstract modifier in the declaration or not?

Answer 31

Yes

Question 32

An interface can have only ________ methods, no ______ methods allowed.

Answer 32

abstract, concrete

Question 33

Interface methods are by default _________ and ______--explicit declaration of these modifiers is optional.

Answer 33

public, abstract

Question 34

(True/False) Interfaces can have constants, which are never public, static, or final.

Answer 34

False, they are always public, static, and final

Question 35

Interface constant declarations of public, static, and final are ________ in any combination.

Answer 35

optional

Question 36

A class implementing an interface can itself be _______.

Answer 36

abstract

Question 37

An abstract implementing class does/does not have to implement the interface methods (but the first concrete subclass must.

Answer 37

does not

Question 38

A class can/cannot extend one class, but it can/cannot implement many interfaces.

Answer 38

can, can

Question 39

Can interfaces extend one or more other interfaces?

Answer 39

yes

Question 40

(True/False) Interfaces cannot extend a class, or implement a class or interface.

Answer 40

true

Question 41

Methods and instance (nonlocal) variables are known as ________?

Answer 41

members

Question 42

Members can use all four access levels. What are those levels?

Answer 42

public, protected, default, and private

Question 43

What are the two forms of member access?

Answer 43

Code in one class can access a member of another class. A subclass can inherit a member of its superclass.

Question 44

(True/False) If a class cannot be accessed, its members can be accessed.

Answer 44

false, its members cannot have access if the class cannot be accessed

Question 45

What should you determine before determining member visibility?

Answer 45

class visibility

Question 46

________ members can be accessed by all other classes, even in other packages.

Answer 46

public

Question 47

If a superclass member is public, the subclass does/does not inherit it--regardless of package.

Answer 47

does

Question 48

Members accessed without the ________ operator must belong to the same class.

Answer 48

Dot

Question 49

"this." always refers to the ___________ executing object.

Answer 49

currently

Question 50

this.aMethod () is the same as just invoking ___________.

Answer 50

aMethod ()

Question 51

(True/False) Private member cannot be accessed by code in the same class.

Answer 51

false, private members can be accessed only by code in the same class

Question 52

Private members are not visible to subclasses, so private members cannot be ________.

Answer 52

inherited

Question 53

Default and protected members differ only when ________ are involved.

Answer 53

subclasses

Question 54

(True/False) Default members can be access only by classes in the same package.

Answer 54

true

Question 55

________ members can be accessed by all other classes in the same package, plus subclasses regardless of package.

Answer 55

protected

Question 56

protected = ________ plus kids (kids meaning subclasses)

Answer 56

package

Question 57

Local (method, automatic, or stack) variable declarations cannot have ______ modifiers.

Answer 57

access

Question 58

________ is the only modifier available to local variables.

Answer 58

final

Question 59

Local variables don't get default values, so they must be ______ before use.

Answer 59

initialized

Question 60

(True/False) Final methods can be overridden in a subclass.

Answer 60

false, they cannot be overridden in a subclass

Question 61

Abstract methods are declared, with a signature, a return type, and an optional throws clause, but are not ______.

Answer 61

implemented

Question 62

Abstract methods end in a _________--no curly braces.

Answer 62

semicolon

Question 63

Name the three ways to spot a non-abstract method.

Answer 63

(1) The method is not marked abstract (2) The method has curly braces (3) The method has code between the curly braces

Question 64

The first nonabstract (concrete) class to extend an ____________ class must implement all of the _______ class' __________ methods.

Answer 64

abstract, abstract, abstract

Question 65

The __________ modifier applies only to methods and code blocks.

Answer 65

synchronized

Question 66

Synchronized methods can have access control and can also be marked ________.

Answer 66

final

Question 67

Abstract methods must be implemented by a subclass, so they must be inheritable. For that reason: (Name both reasons)

Answer 67

(1) abstract methods cannot be private | (2) abstract methods cannot be final

Question 68

The ________ modifier applies only to methods.

Answer 68

native

Question 69

The ________ modifier applies only to classes and methods.

Answer 69

strictfp

Question 70

As of Java 5, methods can declare a ____________ that accepts from zero to many arguments.

Answer 70

parameter

Question 71

A _________ parameter is declared with the syntax type...name; for instance: doStuff (int...x) { }

Answer 71

var-arg

Question 72

A var-arg method can have only one var-gar _______.

Answer 72

parameter

Question 73

(True/False) In methods with normal parameters and a var-arg, the var-arg must come last.

Answer 73

true

Question 74

Instance variable can...

Answer 74

(1) Have any access control (2) Be marked final or transient

Question 75

Instance variables can't be __________, _____________, _____________, or __________.

Answer 75

abstract, synchronized, native, strictfp

Question 76

Is it legal to declare a local variable with the same name as an instance variable (also called "shadowing")?

Answer 76

yes

Question 77

What are the three properties of final variables?

Answer 77

(1) final variables cannot be reinitialized once assigned a value (2) final reference variables cannot refer to a different object once the object has been assigned to the final variable (3) final reference variables must be initialized before the constructor completes

Question 78

(True/False) There is no such thing as a final object.

Answer 78

true--an object reference marked final does not mean the object itself is immutable

Question 79

The transient modifier applies only to _________ variables.

Answer 79

instance

Question 80

The volatile __________ applies only to instance variables.

Answer 80

modifier

Question 81

_________ can hold primitives or objects, but the array itself is always object.

Answer 81

arrays

Question 82

When you _______ an array, the brackets can be to the left or right of the variable name.

Answer 82

declare

Question 83

(True/False) It is always legal to include the size of an array in the declaration.

Answer 83

false--it is never legal to include the size of an array in the declaration

Question 84

An array of object can hold any object that passes the ______ ______ for the declared type of the array.

Answer 84

IS-A test

Question 85

Static variables and methods are/are not tied to any particular instance of a class.

Answer 85

are not

Question 86

No classes instances are needed in order to use ________ members of the class

Answer 86

static

Question 87

________ methods do not have a direct access to non-static members

Answer 87

static

Question 88

An ______ specifies a list of constant values assigned to a type

Answer 88

enum

Question 89

An enum is/is not a String or an int.

Answer 89

is not

Question 90

An enum can be declared outside or inside a class, but not in a ___________.

Answer 90

method

Question 91

An enum declared outside a class must not be marked _______, _______, _______, _______, or _______.

Answer 91

final, abstract, static, protected, private

Question 92

Enums can contact constructors, methods, _______, and constant class bodies.

Answer 92

variables

Question 93

Enum contacts can send ___________ to the enum constructor, using the syntax BIG(8), where the in literal 8 is passed to the enum constructor

Answer 93

arguments

Question 94

(True/False) Enum constructors can never be invoke directly in code.

Answer 94

true

Question 95

MyEnum.values () returns....

Answer 95

an array of MyEnum's values