Exam 18: Generic Classes

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?

To maintain compatibility with pre-generic Java, type parameters are replaced by ordinary types called ____.

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");

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

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

Which of the following is not a wildcard type?

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

Which is the purpose of the <E> element in the class declaration below? public class Thing<E> { Public Thing() { . . . } }

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

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?

Which Java technique(s) allows generic programming? I type variables II primitive types III inheritance

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

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 executing the following code? Box<Boolean> box = new Box<Boolean>(); Box b = (Box) box.getData();

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

Which of the following satisfies the wildcard ? extends Component?

Consider the following code snippet in the LinkedList<E> class: public void addAll(LinkedList<? extends E> other) { ListIterator<E> iter = other.listIterator(); While (iter.hasNext()) { Add(iter.next()); } } Which of the following statements about this code is correct?

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

Which of the following satisfies the wildcard ? super Object?