Question 1

Which of the following statements about hash tables is NOT correct?

Accepted Answer

A) Elements are grouped into smaller collections that share the same characteristic. 
B) You can form hash tables holding objects of type String. 
C) The value used to locate an element in a hash table is called a hash code. 
D) You can add an element to a specific position within a hash table. 
A) Elements are grouped into smaller collections that share the same characteristic. 
B) You can form hash tables holding objects of type String. 
C) The value used to locate an element in a hash table is called a hash code. 
D) You can add an element to a specific position within a hash table.

Question 2

Select an appropriate expression to complete the following code segment, which is designed to print a message if the string stored in name is part of the players collection.

Accepted Answer

A) (players.contains(name)) 
B) (players.indexOf(name)) 
C) (players.search(name)) 
D) (players.equals(name)) 
A) (players.contains(name)) 
B) (players.indexOf(name)) 
C) (players.search(name)) 
D) (players.equals(name))

Question 3

You need to access values using a key, and the keys must be sorted.Which collection type should you use?

Accepted Answer

A) Queue 
B) TreeMap 
C) HashMap 
D) ArrayList 
A) Queue 
B) TreeMap 
C) HashMap 
D) ArrayList

Question 4

Which of the following statements about stacks is correct?

Accepted Answer

A) A stack implements random retrieval. 
B) A stack implements last-in, first-out retrieval. 
C) A stack stores elements in sorted order. 
D) A stack implements first-in, first-out retrieval. 
A) A stack implements random retrieval. 
B) A stack implements last-in, first-out retrieval. 
C) A stack stores elements in sorted order. 
D) A stack implements first-in, first-out retrieval.

Question 5

Consider the code snippet shown below.Assume that employeeNames is an instance of type LinkedList<String>.   Which element(s) of employeeNames does this loop process?

Accepted Answer

A) elements meeting a condition 
B) the most recently added elements 
C) no elements 
D) all elements 
A) elements meeting a condition 
B) the most recently added elements 
C) no elements 
D) all elements

Question 6

Using the merge method of the Map interface, which statement correctly updates the wordCount map of type Map<String,Integer> to count all of the occurrences of a word in a file?

Accepted Answer

A) wordCount.merge(word, 1, (k,v) -> v + 1); 
B) word.merge(wordCount,(k,v) -> v + 1); 
C) word.merge(wordCount, 1, (k,v) -> v + 1); 
D) wordCount.merge(word,(k,v) -> v + 1); 
A) wordCount.merge(word, 1, (k,v) -> v + 1); 
B) word.merge(wordCount,(k,v) -> v + 1); 
C) word.merge(wordCount, 1, (k,v) -> v + 1); 
D) wordCount.merge(word,(k,v) -> v + 1);

Question 7

Assume that you have declared a queue named myQueue to hold String elements.Which of the following statements will correctly delete an element from myQueue?

Accepted Answer

A) myQueue.delete(); 
B) myQueue.remove(); 
C) myQueue.get(); 
D) myQueue.pop(); 
A) myQueue.delete(); 
B) myQueue.remove(); 
C) myQueue.get(); 
D) myQueue.pop();

Question 8

Suppose you push integer elements 1,2,3,4 onto a stack in that order.Then pop an element off the stack and add that element to a queue.You repeat that process three more times.In what order will you remove the elements from the queue?

Accepted Answer

A) 1,2,4,3 
B) 4,3,2,1 
C) 4,3,1,2 
D) 1,2,3,4 
A) 1,2,4,3 
B) 4,3,2,1 
C) 4,3,1,2 
D) 1,2,3,4

Question 9

Assume that you have declared a stack named myStack to hold String elements.Which of the following statements will correctly add an element to myStack?

Accepted Answer

A) myStack.addItem("apple"); 
B) myStack.put("apple"); 
C) myStack.insert("apple"); 
D) myStack.push("apple"); 
A) myStack.addItem("apple"); 
B) myStack.put("apple"); 
C) myStack.insert("apple"); 
D) myStack.push("apple");

Question 10

A list is a collection that ____.

Accepted Answer

A) does not allow elements to be inserted in any position. 
B) only allows items to be added at one end and removed at the other end. 
C) manages associations between keys and values. 
D) should be used when you need to remember the order of elements in the collection. 
A) does not allow elements to be inserted in any position. 
B) only allows items to be added at one end and removed at the other end. 
C) manages associations between keys and values. 
D) should be used when you need to remember the order of elements in the collection.

Question 11

Which of the following statements about a priority queue structure is correct?

Accepted Answer

A) Elements must be removed in priority order. 
B) New items must be inserted at the end of the queue. 
C) It uses a FIFO discipline. 
D) It uses a LIFO discipline. 
A) Elements must be removed in priority order. 
B) New items must be inserted at the end of the queue. 
C) It uses a FIFO discipline. 
D) It uses a LIFO discipline.

Question 12

You need to write a program to simulate the effect of adding an additional cashier in a supermarket to reduce the length of time customers must wait to check out.Which data structure would be most appropriate to simulate the waiting customers?

Accepted Answer

A) map 
B) stack 
C) linked list 
D) queue 
A) map 
B) stack 
C) linked list 
D) queue

Question 13

A collection without an intrinsic order is called a ____.

Accepted Answer

A) queue 
B) stack 
C) set 
D) list 
A) queue 
B) stack 
C) set 
D) list

Question 14

Which of the following statements about manipulating objects in a map is NOT correct?

Accepted Answer

A) Use the remove method to remove a value from the map. 
B) Use the get method to retrieve a value from the map. 
C) Use the keyset method to get the set of keys for the map. 
D) Use the add method to add a new element to the map. 
A) Use the remove method to remove a value from the map. 
B) Use the get method to retrieve a value from the map. 
C) Use the keyset method to get the set of keys for the map. 
D) Use the add method to add a new element to the map.

Question 15

Assuming that names is a Queue of String objects, select a statement to complete the code segment below.The code is designed to remove the last element from the queue, which is guaranteed to have at least one element.

Accepted Answer

A) aQueue.add(names.peek()); 
B) aQueue.add(names.remove()); 
C) names.add(aQueue.peek()); 
D) names.add(aQueue.remove()); 
A) aQueue.add(names.peek()); 
B) aQueue.add(names.remove()); 
C) names.add(aQueue.peek()); 
D) names.add(aQueue.remove());

Question 16

Assume that you have declared a set named mySet to hold String elements.Which of the following statements will correctly delete an element from mySet?

Accepted Answer

A) mySet.delete("apple"); 
B) mySet.remove("apple"); 
C) mySet.get("apple"); 
D) mySet.pop("apple"); 
A) mySet.delete("apple"); 
B) mySet.remove("apple"); 
C) mySet.get("apple"); 
D) mySet.pop("apple");

Question 17

An Undo feature in a word processor program that allows you to reverse a previously completed command is probably implemented using which structure type?

Accepted Answer

A) stack 
B) queue 
C) hash table 
D) linked list 
A) stack 
B) queue 
C) hash table 
D) linked list

Question 18

Which of the following statements about linked lists is correct?

Accepted Answer

A) When a node is removed, all nodes after the removed node must be moved down. 
B) Visiting the elements of a linked list in random order is efficient. 
C) Linked lists should be used when you know the correct position and need to insert and remove elements efficiently. 
D) Even if you have located the correct position, adding elements in the middle of a linked list is inefficient. 
A) When a node is removed, all nodes after the removed node must be moved down. 
B) Visiting the elements of a linked list in random order is efficient. 
C) Linked lists should be used when you know the correct position and need to insert and remove elements efficiently. 
D) Even if you have located the correct position, adding elements in the middle of a linked list is inefficient.

Question 19

A stack is a collection that ____.

Accepted Answer

A) does not remember the order of elements but allows elements to be added in any position. 
B) remembers the order of elements, and allows elements to be added and removed only at one end. 
C) remembers the order of elements and allows elements to be inserted only at one end and removed only at the other end. 
D) remembers the order of elements and allows elements to be inserted in any position. 
A) does not remember the order of elements but allows elements to be added in any position. 
B) remembers the order of elements, and allows elements to be added and removed only at one end. 
C) remembers the order of elements and allows elements to be inserted only at one end and removed only at the other end. 
D) remembers the order of elements and allows elements to be inserted in any position.

Question 20

You need to access values in objects by a key that is not part of the object.Which collection type should you use?

Accepted Answer

A) Hashtable 
B) ArrayList 
C) Map 
D) Queue 
A) Hashtable 
B) ArrayList 
C) Map 
D) Queue

Exam 15: The Java Collections Framework

Which of the following statements about hash tables is NOT correct?

Select an appropriate expression to complete the following code segment, which is designed to print a message if the string stored in name is part of the players collection.

You need to access values using a key, and the keys must be sorted.Which collection type should you use?

Which of the following statements about stacks is correct?

Consider the code snippet shown below.Assume that employeeNames is an instance of type LinkedList<String>. Which element(s) of employeeNames does this loop process?

Using the merge method of the Map interface, which statement correctly updates the wordCount map of type Map<String,Integer> to count all of the occurrences of a word in a file?

Assume that you have declared a queue named myQueue to hold String elements.Which of the following statements will correctly delete an element from myQueue?

Suppose you push integer elements 1,2,3,4 onto a stack in that order.Then pop an element off the stack and add that element to a queue.You repeat that process three more times.In what order will you remove the elements from the queue?

Assume that you have declared a stack named myStack to hold String elements.Which of the following statements will correctly add an element to myStack?

A list is a collection that ____.

Which of the following statements about a priority queue structure is correct?

You need to write a program to simulate the effect of adding an additional cashier in a supermarket to reduce the length of time customers must wait to check out.Which data structure would be most appropriate to simulate the waiting customers?

A collection without an intrinsic order is called a ____.

Which of the following statements about manipulating objects in a map is NOT correct?

Assuming that names is a Queue of String objects, select a statement to complete the code segment below.The code is designed to remove the last element from the queue, which is guaranteed to have at least one element.

Assume that you have declared a set named mySet to hold String elements.Which of the following statements will correctly delete an element from mySet?

An Undo feature in a word processor program that allows you to reverse a previously completed command is probably implemented using which structure type?

Which of the following statements about linked lists is correct?

A stack is a collection that ____.

You need to access values in objects by a key that is not part of the object.Which collection type should you use?

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