Java I/O streams, Files and collection frameworks

Which of the following declarations don't compile?

• A)List<?> l1 = new ArrayList<>();

• B)List<String> l2 = new ArrayList();

• C) List<? super Object> l3 = new ArrayList<String>();

• D) List<? extends Object> l4 = new ArrayList<String>();

public class Question {

public static void main(String[] args) {

Question q = new Question();

List<Integer> l = new ArrayList<>();

l.add(20); l.add(30); q.m1(l); }

private void m1(List<?> l) { m2(l); // 1 }

private <T> void m2(List<T> l)

{ l.set(1, l.get(0)); // 2

System.out.println(l);

}

}

• A) [20, 20]

• B) Compilation fails on the line marked as // 1

• C) Compilation fails on the line marked as // 2

• D) An exception occurs at runtime

public class Question <T extends Number> {

T t;

public static void main(String[] args) {

Question q = new Question<Integer>(); // 1

q.t = new Float(1); // 2

System.out.println(q.t);

}

}

• A. 1.0

• B. Compilation fails on the line marked as // 1

• C. Compilation fails on the line marked as // 2

• D. An exception occurs at runtime

import java.util.*;

class UtilitiesTest {

public static void main(String[] args) {

List < int > intList = new ArrayList < > ();

intList.add(10);

intList.add(20);

System.out.println("The list is: " + intList);

• A) It prints the following: The list is: [10, 20] 

• B) It prints the following: The list is: [20, 10] 

• C. It results in a compiler error 

• D. It results in a runtime exception

Which interface represents a resizable array of objects in Java Collections?

• a) Set

• b) List

• c) Map

• d) Queue

Which of these is not a method defined in the Map interface?

• a) put()

• b) get()

• c) remove()

• d) add()

Which of these interfaces is not part of the Java Collections Framework?

d) Sortable

• a) List

• b) SortedMap

• c) SortedSet

• d) Sortable

Which of these collection classes does not allow duplicate elements?

• a) ArrayList

• b) HashSet

• c) LinkedList

• d) Vector

What is the initial capacity of a HashMap in Java Collections Framework?

• a) 10

• b) 12

• c) 16

• d) 20

What exception is thrown when an object is not found in a PriorityQueue?

• a) ObjectNotFoundException

• b) NoSuchElementException

• c) QueueException

• d) ElementNotFoundException