Question

In Java

1. Which of the following statements declares Salaried as a subclass of payType?

1. Public class Salaried implements PayType
2. Public class Salaried derivedFrom(payType)
3. Public class PayType derives Salaried
4. Public class Salaried extends PayType

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

1. False
2. True

3. When a subclass overloads a superclass method……….

1. Only the subclass method may be called with a subclass object
2. Only the superclass method may be called with a subclass object
3. Both methods may be called with a subclass object
4. Neither method may be called with a subclass object

4. The ……… key word is used to call a superclass constructor explicitly.

1. this
2. extends
3. goto
4. super

5. A subclass may call an overridden superclass method by ………

1. Prefixing its name with the name of the superclass in parentheses
2. Prefixing its name with the super key word and a dot(.)
3. Using the extends key word before the method is called
4. Calling the superclass method first and then calling the subclass method

6. What type of relationship exists between two objects when one object is a specialized version of another object?

1. “contains a”
2. “consists of”
3. “is a”
4. “has a”

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

1. False
2. True

8. 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.”);

}

}

1. It will call the method super and pass the value 40 to it as an argument.
2. This cannot be determined from the code
3. It will call the constructor of ClassA tat receives an integer as an argument.
4. The method super will have to be defined before we can say what will happen.

9. Replacing inadequate superclass methods with more suitable subclass methods is known as……..

1. Method upgrading
2. Tactical inheritance
3. Method overriding
4. Method overloading

10. If ClassC is derived from ClassB which is derived from ClassA, this would be an example of …….

1. Linear inheritance
2. A chain of inheritance
3. Multiple interfaces
4. Cascading classes

11. If two methods have the same name but different signatures they are…….

1. Overridden
2. Overloaded
3. Subclass methods
4. Superclass methods

12. Because every class directly or indirectly inherits from the Object class. Every class inherits the object class’s members

1. False
2. True

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

1. Overrides
2. Overloads
3. Implements
4. Inherits

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

1. True
2. False

15. A(n) ………. Method is a method that appears in a superclass but expects to be overridden in a subclass.

1. Protected
2. Abstract
3. Overloaded
4. Static

16. Given 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();

Item.method1();

1. This is an error and will cause the program to crash
2. method 1 on Line 9
3. method1 on Line 14
4. method1 on Line 4

17. You can write a super statement that calls a superclass constructor but only in the subclass’s constructor.

1. True
2. False

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

1. True
2. False

19. What will happen if a subclass constructor does not explicitly call a superclass constructor?

1. Java will automatically call the superclass’s default constructor immediately after the code in the subclass’s constructor executes
2. Java will automatically call the superclass default constructor just before the code in the subclass constructor executes
3. It must include the code necessary to initialize the superclass fields
4. The superclass fields will be set to the default values for their data types

20. An ArrayList can hold multiple values of several different types of data simultaneously.

1. True
2. False

21. If a[ ] and b[ ] are two integer arrays. The expression a == b compares the array contents.

1. True
2. False

22. The ……. method is used to insert an item into an ArrayList.

1. Store
2. putItem
3. add
4. insert

23. Which of the following ArrayList class methods is used to insert an item at a specific location in an ArrayList?

1. Add
2. Set
3. Store
4. Insert

24. An ArrayList object automatically expands in size to accommodate the items stored in it.

1. True
2. False

25. Objects in an ArrayList are accessed with subscripts, just like an array.

1. False
2. True

Answer 1

Answers:

Which of the following statements declares Salaried as a subclass of payType?
Ans: Public class Salaried extends PayType

If a method in a subclass has the same signature as a method in the superclass, the subclass method overrides the superclass method.
Ans False

When a subclass overloads a superclass method
Ans Both methods may be called with a subclass object

The ……… key word is used to call a superclass constructor explicitly.
Ans: Super

A subclass may call an overridden superclass method by
Ans:Prefixing its name with the super key word and a dot(.)

What type of relationship exists between two objects when one object is a specialized version of another object?
Ans: "is a"

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

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.”);

}

}
Ans: It will call the constructor of ClassA tat receives an integer as an argument.

Replacing inadequate superclass methods with more suitable subclass methods is known as
Ans: Method overriding

If ClassC is derived from ClassB which is derived from ClassA, this would be an example of
Ans: A chain of inheritance

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

Because every class directly or indirectly inherits from the Object class. Every class inherits the object class’s members
True

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

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

A(n) ………. Method is a method that appears in a superclass but expects to be overridden in a subclass.
Abstract

Given 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();
Item.method1();

Ans: method 1 on Line 9

You can write a super statement that calls a superclass constructor but only in the subclass’s constructor.
Ans:False

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

What will happen if a subclass constructor does not explicitly call a superclass constructor?
Java will automatically call the superclass’s default constructor immediately after the code in the subclass’s constructor executes

An ArrayList can hold multiple values of several different types of data simultaneously.
True

If a[ ] and b[ ] are two integer arrays. The expression a == b compares the array contents.
False

The ……. method is used to insert an item into an ArrayList.
add

Which of the following ArrayList class methods is used to insert an item at a specific location in an ArrayList?
Add

An ArrayList object automatically expands in size to accommodate the items stored in it.
True

Objects in an ArrayList are accessed with subscripts, just like an array.
True

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