3.3 Java3002r review  (Page 3/5)

Answer 26

Question 27

True or False? The class that begins in Listing 5 does not have an access modifier. This puts it in package-private access category. A class with package-private access can be accessed by codethat is stored in the same package and cannot be accessed by code stored in other packages.

Answer 27

Question 28

True or False? The last three statements in Listing 5 declare three private variables. Because these variables are declared private, they can be accessed by any method defined in any class in thesame package.

Answer 28

Question 29

True or False? The three variables declared in Listing 5 are instance variables as opposed to class variables .

Answer 29

Question 30

True or False? Because the three variables declared in Listing 5 are instance variables, they belong to an object instantiated from the class. Even if the variables were public, they could onlybe accessed by first gaining access to the object to which they belong.

Answer 30

Question 31

True or False? The three variables declared in Listing 5 are reference variables . This means that they are capable of storing references to objects and are also capable of storing values of the eightprimitive types.

Answer 31

Question 32

True or False? Ericson's class library contains a class named World and another class named Turtle . The code in Listing 5 instantiates one object of the World class and populates that world with three objects of the Turtle class.

Answer 32

Question 33

True or False? Every class definition has one or more method-like members called constructors. (If you don't define a constructor when you define a class, a default constructor will be automatically defined for your class.)

Answer 33

Question 34

True or False? The name of the constructor must always be the same as the name of the class in which it is defined. Like a method, a constructor may ormay not take arguments. If there are two or more (overloaded) constructors, they must have different argument lists.

Answer 34

Question 35

True or False? To instantiate an object of a class, you apply the new operator to the class' constructor, passing parameters that satisfy the requiredarguments for the constructor.

Answer 35

Question 36

True or False? When an object is instantiated, the constructor returns an array containing the values in all of the instance variables.

Answer 36

Question 37

True or False? The last two statements in Listing 5 instantiate two objects of the Turtle class and use them to populate the World object whose reference is stored in the variable named mars .

Answer 37

Question 38

True or False? If a variable (exclusive of local variables inside of methods) is not purposely initialized when the object in instantiated, it will receive a default initialization value. The default values are:

• 0 or 0.0 for numeric variables
• true for boolean variables
• null for reference variables

Answer 38

Question 39

True or False? Code written into a class' constructor is executed when an object of the class is instantiated.

Answer 39

Question 40

True or False? Good object-oriented programming practice says that most of the instance variables encapsulated in an object should be declared private. Ifthere is a need to make the contents of those variables available outside the object, that should be accomplished by defining protected accessor methods.