Question 1

Consider the following code snippet that declares the GraduateStudent class: public GraduateStudent extends Student { . . .} Which of these statements are false? I GraduateStudent is a subclass of Student II Stack is a subclass of Stack III Stack is a subclass of Stack

Accepted Answer

GraduateStudent is a subclass of Student, so Stack is a subclass of Stack. However, Stack is not a subclass of Stack.

Question 2

Which of the following statements about generic methods is correct?

Accepted Answer

Generic methods in Java cannot use primitive types directly as type parameters; they must use their wrapper classes instead.

Question 3

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};
String[] s = {"happy","cat","silly","dog"};
Boolean[] b = {"true", "true", "false"};
Which of the following are correct calls to this generic print method?
I print(a);
II print(s);
III print(b);

Accepted Answer

The answer of Consider the following code snippet: public static...

Question 4

Determine the correctness of the MyLinkedList generic class code below. public class MyLinkedList<E>
{
Private MyNode first;
Public E getFirst() { return first.data; }
Private class MyNode
{
Private E data;
Private MyNode next;
}
}

Accepted Answer

The code is correct. The inner class MyNode can be private, and first.data will not cause a compiler error because first is of type MyNode, which has a data field of type E.

Question 5

Which of the following statements about generic methods is correct?

Accepted Answer

A generic method must have a generic type parameter, which allows it to operate on different data types. This parameter is specified in the method's signature.

Question 6

Consider our own generic class MyLinkedList shown below. It has a private Node class, and it implements the standard Java ListIterator generic interface. public class MyLinkedList { Private MyNode first; ) . . Private class MyNode { Private E data; Private MyNode next; } Private class MyIterator implements ListIterator { ) . . } } Which of the following statements apply? I the code is correct II change to private class MyIterator implements ListIterator III change to private class MyNode

Accepted Answer

The code is correct. The MyNode class is private to the MyLinkedList class, and the MyIterator class implements the ListIterator interface.

Question 7

An inner helper class, such as a TreeNode inside the generic BinaryTree class, must meet which of the following criteria?
I be public
II be private
III be declared as generic

Accepted Answer

An inner helper class does not have to meet any specific criteria such as being public, private, or declared as generic. These are design choices based on the intended use and encapsulation needs.

Question 8

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

Generic methods do not need to be declared inside a generic class, do not need to be static, and can have more than one generic parameter.

Question 9

What is known for certain about a type parameter when a method constrains it as follows? <E extends MouseListener & MouseMotionListener>

Accepted Answer

The type parameter E is constrained to implement both MouseListener and MouseMotionListener interfaces.

Question 10

Which of these Java library classes are implemented using type variables?
I HashMap
II LinkedList
III ArrayList

Accepted Answer

All three classes, HashMap, LinkedList, and ArrayList, are implemented using type variables (generics) in Java to allow them to store objects of any type.

Question 11

Determine the output of the MyLinkedList generic class code below when the main method executes. public class MyLinkedList<E>
{
Private MyNode first;
Public MyLinkedList(E

Accepted Answer

The constructor of MyLinkedList initializes the first node with the data "Hello", so the output will be "List first element = Hello".

Question 12

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

The LinkedList class can use any generic type parameter name, such as S or Element, as long as it is consistent within the class definition.

Question 13

Given the following generic method, which of the following is a possible return type? public static <E extends Comparable> E max(E[]A) { . . . }
I String
II Object
III Double

Accepted Answer

The method requires a type that extends Comparable. String and Double both implement Comparable, making them valid return types. Object does not implement Comparable, so it is not a valid return type.

Question 14

The type variables in HashMap<K, V> in the standard library mnemonically represent ____.

Accepted Answer

In a HashMap<K, V>, K stands for "key" and V stands for "value", representing the key-value pairs stored in the map.

Question 15

Which argument type cannot passed to generic methods?
I Object
II GUI components
III primitive

Accepted Answer

Generic methods cannot accept primitive types as arguments because generics work with objects, and primitive types are not objects.

Question 16

Given the following generic method, which of the following CANNOT be the return type? public static <E extends Comparable> E max(E[]A) { . . .}
I String
II Integer
III double

Accepted Answer

The method requires a type that extends Comparable. The primitive type 'double' cannot be used as it does not implement Comparable.

Question 17

What is the best technique for overcoming the restriction for the use of primitives, such as int, in generic classes and methods?

Accepted Answer

Wrapper classes allow primitives to be used in generic classes and methods by providing an object representation of the primitive data types.

Question 18

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

The code attempts to cast a String object to a Double, which is not allowed and will result in a ClassCastException.

Question 19

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

Accepted Answer

The syntax `<E extends Visualizer>` allows `Visualizer` to be either a class or an interface. The `extends` keyword in Java generics is used for both classes and interfaces.

Question 20

In Java, generic programming can be achieved with ____.

Accepted Answer

The answer of In Java, generic programming can be achieved...

Quiz 18: Generic Classes

Which of the following statements about generic methods is correct?

Determine the correctness of the MyLinkedList generic class code below. public class MyLinkedList<E> { Private MyNode first; Public E getFirst() { return first.data; } Private class MyNode { Private E data; Private MyNode next; } }

Which of the following statements about generic methods is correct?

An inner helper class, such as a TreeNode inside the generic BinaryTree class, must meet which of the following criteria? I be public II be private III be declared as generic

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.

What is known for certain about a type parameter when a method constrains it as follows? <E extends MouseListener & MouseMotionListener>

Which of these Java library classes are implemented using type variables? I HashMap II LinkedList III ArrayList

Determine the output of the MyLinkedList generic class code below when the main method executes. public class MyLinkedList<E> { Private MyNode first; Public MyLinkedList(E

Given the following generic method, which of the following is a possible return type? public static <E extends Comparable> E max(E[]A) { . . . } I String II Object III Double

The type variables in HashMap<K, V> in the standard library mnemonically represent ____.

Which argument type cannot passed to generic methods? I Object II GUI components III primitive

Given the following generic method, which of the following CANNOT be the return type? public static <E extends Comparable> E max(E[]A) { . . .} I String II Integer III double

What is the best technique for overcoming the restriction for the use of primitives, such as int, in generic classes and methods?

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

In Java, generic programming can be achieved with ____.