Exam 18: Generic Classes

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

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

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<GraduateStudent> is a subclass of Stack<Student> III.Stack<Student> is a subclass of Stack<GraduateStudent>

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 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<E> { private MyNode first; ... private class MyNode { private E data; private MyNode next; } private class MyIterator implements ListIterator<E> { ... } } 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<E>

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

Consider the following declaration: LinkedList<String> list = new LinkedList<>(); This declaration implies that the LinkedList class could begin with which of the following code statements? i.public class LinkedList<String> { ...} II.public class LinkedList<S> { ...} III.public class LinkedList<Element> { ...}

Consider the following code snippet: public static void reverse(List<?> list) { ...} This method declaration is equivalent to which of the following declarations?

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 void reverse(List <?> list) { ...} Which of the following statements about this code is correct?

Consider the following code snippet: public interface MyInterface<E> { ...} public interface YourInterface<E, T> extends MyInterface<E> { ...} Which of these are legal class declarations? i.public class SomeClass implements YourInterface<String, Double> { ...} II.public class SomeClass implements YourInterface { ...} III.public class SomeClass implements YourInterface<String> { ...}

Consider the following code snippet: public static void reverse(List <? extends E> list) { ...} Which of the following statements about this code is correct?

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 e) { first = new MyNode(); first.data = e; first.next = null; } public E getFirst() { return first.data; } private class MyNode { private E data; private MyNode next; } public static void main(String[] args) { MyLinkedList<String> list = new MyLinkedList<>("Hello"); System.out.println("List first element = " + list.getFirst()); } }

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

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

What does it mean when the syntax ? super D is used?

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?

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

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

What does the following code snippet mean: <E extends Comparable<E> & Measurable>