Question 1

Consider the following code snippet: Public class LinkedList { Private E defaultValue; Public static List replicate(E value, int n) { . . . } Private class Node { public String data; public Node next;) ) . . } What is wrong with this code?

Accepted Answer

A)   Cannot declare the variable defaultValue as a generic type.
B)   Cannot pass a generic type as an argument to a method.
C)   Cannot have a static method in a generic class as shown.
D)   Cannot have an inner class in a generic class. C

Question 2

Consider the following code snippet:
Public class LinkedList<E>
{
Private E defaultValue; //Line 1
Public void add(E value, int n) { . . . } //Line 2
Private static class Node { public E data; public Node next;)//Line 3
) . .
}
What is wrong with this code?

Accepted Answer

A)   Cannot declare the variable defaultValue as a generic type.
B)   Cannot pass a generic type as an argument to a method.
C)   Cannot have a static method in a generic class as shown.
D)   Cannot have a static inner class in a generic class as shown. D

Question 3

Consider the following code snippet: ArrayList coins1 = new ArrayList(); //Line 1 LinkedList coins2 = new LinkedList(); //Line 2 Coins1.add("my penny"); //Line 3 Coins2.addFirst("my penny"); //Line 4 Which of the above lines will cause a compile-time error?

Accepted Answer

A)   Line 1
B)   Line 2
C)   Line 3
D)   Line 4 C

Question 4

What is known for certain about Visualizer when a method constrains its type parameter as follows?
<E extends Visualizer>

Accepted Answer

A)   Visualizer must refer to a class
B)   Visualizer must refer to an interface
C)   Visualizer can refer to either an interface or a class
D)   Visualizer is another generic type

Question 5

If a class requires two generic type variables, how many can you legally provide in Java?
I 0
II 1
III 2

Accepted Answer

A)   I
B)   II
C)   I and II
D)   I and III

Question 6

Which Java generic programming technique(s) requires the programmer to use casting to access variables stored as Object types?
I type variables
II primitive types
III inheritance

Accepted Answer

A)   I
B)   II
C)   III
D)   I and III

Question 7

Consider the following code snippet: ArrayList coins1 = new ArrayList(); //Line 1 LinkedList coins2 = new LinkedList(); //Line 2 Coins1.add("my penny"); //Line 3 Coins2.addFirst("my penny"); //Line 4 Which of the above lines will cause a run-time error when the object is retrieved elsewhere in the program?

Accepted Answer

A)   Line 1
B)   Line 2
C)   Line 3
D)   Line 4

Question 8

Consider the following declaration: LinkedList list = new LinkedList(); This declaration implies that the LinkedList class could begin with which of the following code statements? I public class LinkedList { . . . } II public class LinkedList ~~{ . . . } III public class LinkedList { . . . }~~

Accepted Answer

A)   I
B)   II
C)   III
D)   II and III

Question 9

Consider the following code snippet:
Public static <E extends Measurable> E min(E[] objects)
Which of the following represents the result of type erasure on this code?

Accepted Answer

A)   public static Measurable E min(Measurable E[] objects) 
B)   public static Measurable min(Measurable[] objects) 
C)   public static <Measurable E> E min(Measurable E[] objects) 
D)   This code is illegal and type erasure will not occur.

Question 10

In Java, generic programming can be achieved with ____.

Accepted Answer

A)   encapsulation
B)   inheritance
C)   polymorphism
D)   arrays

Question 11

Which of the following satisfies the wildcard ? extends Object?
I String
II JComponent
III Scanner

Accepted Answer

A)   I
B)   II
C)   I and II
D)   I, II and III

Question 12

Consider the following code snippet: Public class Box { Private E data; Public Box() { . . . } Public void insert(E value) { . . . } } What will result from executing the following code? Box box = new Box(); Box)insert("blue Box");

Accepted Answer

A)   compile-time error
B)   run-time error
C)   correct generic assignment
D)   compile-time warning

Question 13

Which of the following necessitates the type erasure process?
I The Java virtual machine does not work with generic types
II To maintain backward compatibility to older versions of Java
III Generics do not work with primitives

Accepted Answer

A)   I
B)   II
C)   I and II
D)   I and III

Question 14

Consider the following code snippet: Public class Box { Private E data; Public Box(){ . . . } Public void insert(E value) { . . . } } Which of the following is a valid Box object instantiation? I Box

Accepted Answer

A)   I
B)   I and II
C)   I and III
D)   II and III

Question 15

Consider the following code snippet: Public class Box { Private E data; Public Box(){ . . . } Public void insert(E value) { . . . } Public E getData(){ . . . } } What specific exception will be thrown when the following code executes? Box box = new Box(); ) . . Box)insert("blue Box"); Double myDouble = (Double) box.getData();

Accepted Answer

A)   Exception
B)   NoSuchElementException
C)   IndexOutOfBoundsException
D)   ClassCastException

Question 16

Which of the following statements regarding restrictions for generic methods are true?
I Generic methods must be declared inside a generic class.
II Generic methods must be static.
III Generic methods may only have one generic parameter.

Accepted Answer

A)   I
B)   I and II
C)   II and III
D)   none are restrictions

Question 17

Consider the following code snippet: Public class Box { Private E data; Public Box(){ . . . } } Which of the following is a valid Box object instantiation?

Accepted Answer

A) Box box = new Box; B) Box box = new Box() ; C) Box box = new Box() ; D) Box box = new Box() ;

Question 18

Consider the following code snippet:
Public static <E> void print(E[] a)
{
For (int i = 0; i < a.length; i++)
{
System.out.println(a[i] + " ");
}
}
Int[] a = {3,6,5,7,8,9,2,3};
Print(makeArray(a));
Assume that the method call to print(makeArray(a)) works correctly by printing the int array a. Which of the following headers for the makeArray method will make this possible?
I public static Integer[] makeArray(int[] a) 
II public static E[] makeArray(int[] a) 
III public static Integer[] makeArray(E[] a)

Accepted Answer

A)   I
B)   I and II
C)   II and III
D)   I and III

Question 19

Consider the following code snippet: Public class Box { Private E data; Public Box() { . . . } Public void insert(E value) { . . . } Public E getData(){ . . . } } What will result from the following code? Box box = new Box(); ) . . Box)insert("blue Box"); Double myDouble = (Double) box.getData();

Accepted Answer

A)   compiler error
B)   run-time error
C)   correct, but unnecessary cast
D)   correct, with necessary cast

Question 20

Consider the following class declaration:
Public class SavingsAccount extends BankAccount { . . . }
Which of the following statements about these classes is correct?

Accepted Answer

A) ArrayList is a subclass of ArrayList. B) ArrayList is a subclass of ArrayList. C) ArrayList extends ArrayList. D) There is no relationship between ArrayList and ArrayList

Exam 18: Generic Classes

Consider the following code snippet: Public class LinkedList<E> { Private E defaultValue; Public static List<E> replicate(E value, int n) { . . . } Private class Node { public String data; public Node next;) ) . . } What is wrong with this code?

Consider the following code snippet: Public class LinkedList<E> { Private E defaultValue; //Line 1 Public void add(E value, int n) { . . . } //Line 2 Private static class Node { public E data; public Node next;) //Line 3 ) . . } What is wrong with this code?

Consider the following code snippet: ArrayList<Coin> coins1 = new ArrayList<Coin>() ; //Line 1 LinkedList coins2 = new LinkedList() ; //Line 2 Coins1.add("my penny") ; //Line 3 Coins2.addFirst("my penny") ; //Line 4 Which of the above lines will cause a compile-time error?

What is known for certain about Visualizer when a method constrains its type parameter as follows? <E extends Visualizer>

If a class requires two generic type variables, how many can you legally provide in Java? I 0 II 1 III 2

Which Java generic programming technique(s) requires the programmer to use casting to access variables stored as Object types? I type variables II primitive types III inheritance

Consider the following code snippet: Public static <E extends Measurable> E min(E[] objects) Which of the following represents the result of type erasure on this code?

In Java, generic programming can be achieved with ____.

Which of the following satisfies the wildcard ? extends Object? I String II JComponent III Scanner

Consider the following code snippet: Public class Box<E> { Private E data; Public Box() { . . . } Public void insert(E value) { . . . } } What will result from executing the following code? Box<Boolean> box = new Box<Boolean>() ; Box) insert("blue Box") ;

Which of the following necessitates the type erasure process? I The Java virtual machine does not work with generic types II To maintain backward compatibility to older versions of Java III Generics do not work with primitives

Which of the following statements regarding restrictions for generic methods are true? I Generic methods must be declared inside a generic class. II Generic methods must be static. III Generic methods may only have one generic parameter.

Consider the following code snippet: Public class Box<E> { Private E data; Public Box() { . . . } } Which of the following is a valid Box<E> object instantiation?

Consider the following class declaration: Public class SavingsAccount extends BankAccount { . . . } Which of the following statements about these classes is correct?