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: 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 run-time error when the object is retrieved elsewhere in the program?

Consider the following declaration: LinkedList<String> list = new LinkedList<String>(); 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 <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

Consider the following code snippet: Public class Box<E> { Private E data; Public Box(){ . . . } Public void insert(E value) { . . . } } Which of the following is a valid Box<E> object instantiation? I Box<Object> box = new Box<Object>(); II Box<Boolean> box = new Box<Boolean>(); III Box<double> box = new Box<double>();

Consider the following code snippet: Public class Box<E> { 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<String> box = new Box<String>(); ) . . Box)insert("blue Box"); Double myDouble = (Double) box.getData();

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 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)

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

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