Java Chapter 9 Written Review

When an "is a" relationship exists between objects, it means that the specialized object has:

Which of the following statements declares Salaried as a subclass of PayType? a. public class Salaried extends PayType b. public class Salaried implements PayType c. public class Salaried derivedFrom(Paytype) d. public class PayType derives Salaried

If ClassA extends ClassB, then: a. public and private members of ClassB are public and private, respectively, in ClassA b. public members in ClassB are public in ClassA, but private members in ClassB cannot be directly accessed in ClassA c. neither public or private members in ClassB can be directly accessed in ClassA d. private members in ClassB are changed to protected members in ClassA

In an inheritance relationship:

In UML diagrams, inheritance is shown:

What key word can you use to call a superclass constructor explicitly?

What is wrong with the following code? public class ClassB extends ClassA { public ClassB() { int init = 10; super(40); } }

Look at the following code and determine what the call to super will do. public class ClassB extends ClassA { public ClassB() { super(10); } }

If a subclass constructor does not explicitly call a superclass constructor:

The super statement that calls the superclass constructor:

Replacing inadequate superclass methods with more suitable subclass methods is known as what?

If two methods have the same name but different signatures, they are:

Look at the following code. The method in line _______ will override the method in line _______. Line 1 public class ClassA Line 2 { Line 3 public ClassA() {} Line 4 public int method1(int a){} Line 5 public double method2(int b){} Line 6 } Line 7 public ClassB extends ClassA Line 8 { Line 9 public ClassB(){} Line 10 public int method1(int b, int c){} Line 11 public double method2(double c){} Line 12 }

Look at the following code. Which line will cause a compiler error? Line 1 public class ClassA Line 2 { Line 3 public ClassA() {} Line 4 public final int method1(int a){} Line 5 public double method2(int b){} Line 6 } Line 7 public ClassB extends ClassA Line 8 { Line 9 public ClassB(){} Line 10 public int method1(int b){} Line 11 public double method2(double c){} Line 12 }

When a subclass overloads a superclass method:

A protected member of a class may be directly accessed by: a. methods of the same class b. methods of a subclass c. methods in the same package d. All of the above.

When declaring class data members, it is best to declare them as:

If you do not provide an access specifier for a class member, the class member is given ___________ by default.

When a method is declared with the ____________ modifier, it cannot be overridden in a subclass.

If ClassC extends ClassB, which extends ClassA, this would be an example of:

Line 1 public class ClassA Line 2 { Line 3 public ClassA() {} Line 4 public void method1(){} Line 5 } Line 6 public class ClassB extends ClassA Line 7 { Line 8 public ClassB(){} Line 9 public void method1(){} Line 10 } Line 11 public class ClassC extends ClassB Line 12 { Line 13 public ClassC(){} Line 14 public void method1(){} Line 15 } Which method1 will be executed as a result of the following statements? ClassA item1 = new ClassC(); item1.method1();

Look at the following code. Line 1 public class ClassA Line 2 { Line 3 public ClassA() {} Line 4 public void method1(int a){} Line 5 } Line 6 public class ClassB extends ClassA Line 7 { Line 8 public ClassB(){} Line 9 public void method1(){} Line 10 } Line 11 public class ClassC extends ClassB Line 12 { Line 13 public ClassC(){} Line 14 public void method1(){} Line 15 } Which method will be executed as a result of the following statements? ClassB item1 = new ClassA(); item1.method1();

If a class contains an abstract method: a. you cannot create an instance of the class b. the method will have only a header, but not a body, and end with a semicolon c. the method must be overridden in subclasses d. All of the above

Given the following code which of the following is true? public class ClassB implements ClassA{} a. ClassA must override each method in ClassB b. ClassB must override each method in ClassA c. ClassB inherits from ClassA d. ClassA inherits from ClassB

All fields declared in an interface:

Look at the following code. Which line has an error? Line 1 public interface Interface1 Line 2 { Line 3 int FIELDA = 55; Line 4 public int methodA(double){} Line 5 }

Look at the following code. Which line in ClassA has an error: Line 1 public interface MyInterface Line 2 { Line 3 int FIELDA = 55; Line 4 public int methodA(double); Line 5 } Line 6 public class ClassA implements MyInterface Line 7 { Line 8 FIELDA = 60; Line 9 public int methodA(double) { } Line 10 }

Look at the following code. What is missing from ClassA? Line 1 public interface MyInterface Line 2 { Line 3 int FIELDA = 55; Line 4 public int methodA(double); Line 5 } Line 6 public class ClassA implements MyInterface Line 7 { Line 8 FIELDA = 60; Line 9 public int methodB(double) { } Line 10 }

When one object is a specialized version of another object, there is this type of relationship between them.

A subclass can directly access:

In the following statement, which is the superclass? public class ClassA extends ClassB implements ClassC

A subclass may call an overridden superclass method by:

In the following statement, which is the subclass? public class ClassA extends ClassB implements ClassC

In the following statement, which is the interface? public class ClassA extends ClassB implements ClassC

What is wrong with the following code? public class ClassB extends ClassA { public ClassB() { super(40); System.out.println("This is the last statement " + "in the constructor."); } }

In the following code, what will the call to super do? public class ClassB extends ClassA { public ClassB() { super(40); System.out.println("This is the last statement "+ "in the constructor."); } }

If a superclass does not have a default constructor or a no-arg constructor:

Look at the following code. The method in line ________ will override the method in line __________. Line 1 public class ClassA Line 2 { Line 3 public ClassA() {} Line 4 public int method1(int a){} Line 5 public int method2(int b){} Line 6 } Line 7 public ClassB extends ClassA Line 8 { Line 9 public ClassB(){} Line 10 public int method1(int b){} Line 11 public int method2(double c){} Line 12 }

Look at the following code. Which line will cause a compiler error? Line 1 public class ClassA Line 2 { Line 3 public ClassA() {} Line 4 public int method1(int a){} Line 5 public final int method2(double b){} Line 6 } Line 7 public ClassB extends ClassA Line 8 { Line 9 public ClassB(){} Line 10 public int method1(int b){} Line 11 public int method2(double c){} Line 12 }

Protected members are: a. not quite private b. not quite public c. Both A and B d. Neither A or B

Protected class members are denoted in a UML diagram with the symbol

Which of the following is true about protected access?

Like a family tree, a ____________ shows the inheritance relationship between classes. a. flowchart b. class map c. class hierarchy d. binary tree

In a class hierarchy:

Look at the following code: Line 1 public class ClassA Line 2 { Line 3 public ClassA() {} Line 4 public void method1(int a){} Line 5 } Line 6 public class ClassB extends ClassA Line 7 { Line 8 public ClassB(){} Line 9 public void method1(){} Line 10 } Line 11 public class ClassC extends ClassB Line 12 { Line 13 public ClassC(){} Line 14 public void method1(){} Line 15 } Which method1 will be executed when the following statements are executed? ClassA item1 = new ClassB(); item1.method1();

Look at the following code: Line 1 public class ClassA Line 2 { Line 3 public ClassA() {} Line 4 public void method1(int a){} Line 5 } Line 6 public class ClassB extends ClassA Line 7 { Line 8 public ClassB(){} Line 9 public void method1(){} Line 10 } Line 11 public class ClassC extends ClassB Line 12 { Line 13 public ClassC(){} Line 14 public void method1(){} Line 15 } Which method will be executed when the following statements are executed? ClassC item1 = new ClassA(); item1.method1();

If a class contains an abstract method:

In an interface all methods have:

Which of the following statements correctly specifies three interfaces? a. public class ClassA implements Interface1, Interface2, Interface3 b. public class ClassA implements [Interface1, Interface2, Interface3] c. public class ClassA implements (Interface1, Interface2, Interface3) d. public class ClassA implements Interface1 Interface2 Interface3

Inheritance involves a subclass, which is the general class, and a superclass, which is the specialized class.

Private members of the superclass cannot be accessed by the subclass.

It is not possible for a superclass to call a subclass's method.

When a subclass extends a superclass, the public members of the superclass become public members of the subclass.

If a method in a subclass has the same signature as a method in the superclass, the subclass method overloads the superclass method.

Every class is either directly or indirectly derived from the Object class.

An abstract class is not instantiated, but serves as a superclass for other classes.

In an inheritance relationship, the subclass constructor always executes before the superclass constructor.

If two methods in the same class have the same name but different signatures, the second overrides the first.

Every class has a toString method and an equals method inherited from the Object class.

All methods in an abstract class must also be declared abstract.

When an interface variable references an object, you can use the interface variable to call any and all of the methods in the class implementing the interface.