Question 1

Generics limit Java code somewhat. Which of the following are considered limitations of generic code?
I cannot have an array of a generic type
II cannot have primitive type variables
III cannot construct an object of a generic type

Accepted Answer

Generics in Java have several limitations: you cannot create arrays of a generic type, you cannot use primitive types as type parameters, and you cannot instantiate a generic type directly.

Question 2

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

Type erasure removes all type parameters, so the result is:public static Measurable min(Measurable[] objects)

Question 3

Consider the following code snippet: public interface MyInterface { . . . } Public interface YourInterface extends MyInterface { . . . } Which of these are legal class declarations? I public class SomeClass implements YourInterface { . . . } II public class SomeClass implements YourInterface { . . . } III public class SomeClass implements YourInterface { . . . }

Accepted Answer

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

Question 4

Generics limit Java code somewhat. Which of the following are limitations of generic code?
I cannot declare static variables of a generic type
II cannot declare static methods of a generic type
III cannot declare static inner classes of a generic type

Accepted Answer

Generic code cannot declare static variables, static methods, or static inner classes of a generic type.

Question 5

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

Static methods in a generic class cannot use the class's generic type parameters unless they are passed as parameters to the method itself.

Question 6

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

Accepted Answer

The answer of If a class requires two generic type...

Question 7

Suppose a generic method accepts a generic unconstrained argument p. What restrictions are placed on p by the compiler?

Accepted Answer

When a generic method accepts an unconstrained argument, it can only execute methods available in the Object class, as there are no specific type constraints provided.

Question 8

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

Type erasure is necessary because the Java virtual machine does not work with generic types (I) and to maintain backward compatibility with older versions of Java (II).

Question 9

What is the result when a program constructs a generic class without passing a type variable, as in the following code? Stack stack = new Stack();
I the program will compile and run
II the compiler will issue an error
III the compiler will issue a warning

Accepted Answer

The program will compile and run, but the compiler will issue a warning because the generic type is not specified, leading to the use of raw types.

Question 10

Which of the following are restrictions of Java generic programming?
I You cannot use the assignment operator = to assign one generic object to another.
II You cannot use the == operator to compare two generic objects.
III You cannot construct arrays of generic types.

Accepted Answer

Java does not allow the creation of arrays of generic types due to type erasure and the inability to enforce type safety at runtime.

Question 11

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

Accepted Answer

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

Question 12

Given the following declaration, what is the type parameter in Stack<E> replaced with? private Stack myStack = new Stack();

Accepted Answer

The type parameter in Stack<E> is replaced with Object when no specific type is provided, as in the case of a raw type declaration like Stack.

Question 13

Given the following declaration, what is the type parameter in Stack replaced with? private Stack myStack = new Stack();

Accepted Answer

The type parameter E in Stack<E> is replaced with String in the declaration, making myStack a Stack of Strings.

Question 14

Consider the following code snippet: public static <T> void fun(T[] t) { . . . }
Erasure by the compiler of method fun will generate which result?

Accepted Answer

The erasure of a generic method replaces the type parameter with its bound, which is Object if no bound is specified. Thus, the method becomes public static void fun(Object[] t).

Question 15

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

Static inner classes in a generic class cannot use the generic type parameter of the outer class.

Quiz 18: Generic Classes

Generics limit Java code somewhat. Which of the following are considered limitations of generic code? I cannot have an array of a generic type II cannot have primitive type variables III cannot construct an object of a generic type

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?

Generics limit Java code somewhat. Which of the following are limitations of generic code? I cannot declare static variables of a generic type II cannot declare static methods of a generic type III cannot declare static inner classes of a generic type

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?

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

Suppose a generic method accepts a generic unconstrained argument p. What restrictions are placed on p by the compiler?

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

What is the result when a program constructs a generic class without passing a type variable, as in the following code? Stack stack = new Stack() ; I the program will compile and run II the compiler will issue an error III the compiler will issue a warning

Which of the following are restrictions of Java generic programming? I You cannot use the assignment operator = to assign one generic object to another. II You cannot use the == operator to compare two generic objects. III You cannot construct arrays of generic types.

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

Given the following declaration, what is the type parameter in Stack<E> replaced with? private Stack myStack = new Stack() ;

Given the following declaration, what is the type parameter in Stack<E> replaced with? private Stack<String> myStack = new Stack<String>() ;

Consider the following code snippet: public static <T> void fun(T[] t) { . . . } Erasure by the compiler of method fun will generate which result?

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?