Question 1

Collections method sort that accepts a List as an argument. It sorts the List elements, which must implement the __________ interface.

Accepted Answer

A)  Comparable. 
B)  Comparator. 
C)  Compare. 
D)  Ordering. 
A)  Comparable. 
B)  Comparator. 
C)  Compare. 
D)  Ordering.

Question 2

Comparator method compare should return ________ if the first argument is greater than the second argument.

Accepted Answer

A)  a positive int value. 
B)  zero. 
C)  a negative int value. 
D)  a String. 
A)  a positive int value. 
B)  zero. 
C)  a negative int value. 
D)  a String.

Question 3

Java supports type inferencing with the <> notation in statements that declare and create generic type variables and objects. For example, the following line: List list = new ArrayList(); Can be written as:

Accepted Answer

A) List<> list = new ArrayList<>(); B) List<> list = new ArrayList(); C) List list = new ArrayList<>(); D) List list = new ArrayList(); A) List<> list = new ArrayList<>(); B) List<> list = new ArrayList(); C) List list = new ArrayList<>(); D) List list = new ArrayList();

Question 4

Stack method __________ looks at the top element of a stack without removing that element.

Accepted Answer

A)  glance. 
B)  peek. 
C)  look. 
D)  sample. 
A)  glance. 
B)  peek. 
C)  look. 
D)  sample.

Question 5

Which statement is false?

Accepted Answer

A)  When a List is backed by an array, any modifications made through the List view change the array. 
B)  When a List is backed by an array, any modifications made to the array change the List view. 
C)  The only operation permitted on the view returned by Arrays method asList is delete, which deletes the value from the view and the backing array. 
D)  Adding elements to the view returned by Arrays method asList results in an UnsupportedOperationException. 
A)  When a List is backed by an array, any modifications made through the List view change the array. 
B)  When a List is backed by an array, any modifications made to the array change the List view. 
C)  The only operation permitted on the view returned by Arrays method asList is delete, which deletes the value from the view and the backing array. 
D)  Adding elements to the view returned by Arrays method asList results in an UnsupportedOperationException.

Question 6

Which statement is false?

Accepted Answer

A)  The Collections API provides a set of public static methods for converting collections to unmodifiable versions. 
B)  Unmodifable wrappers throw ModificationExceptions if attempts are made to modify the collection. 
C)  You can use an unmodifiable wrapper to create a collection that offers read-only access to others while allowing read-write access to yourself. 
D)  You can create the kind of collection mentioned in part (c) simply by giving others a reference to the unmodifiable wrapper while you also retain a reference to the wrapped collection itself. 
A)  The Collections API provides a set of public static methods for converting collections to unmodifiable versions. 
B)  Unmodifable wrappers throw ModificationExceptions if attempts are made to modify the collection. 
C)  You can use an unmodifiable wrapper to create a collection that offers read-only access to others while allowing read-write access to yourself. 
D)  You can create the kind of collection mentioned in part (c) simply by giving others a reference to the unmodifiable wrapper while you also retain a reference to the wrapped collection itself.

Question 7

A Properties object is a __________ Hashtable object.

Accepted Answer

A)  transient. 
B)  persistent. 
C)  polymorphic. 
D)  protected. 
A)  transient. 
B)  persistent. 
C)  polymorphic. 
D)  protected.

Question 8

If the desired Object is not found, binarySearch returns __________.

Accepted Answer

A)  a positive value 
B)  zero 
C)  a negative value 
D)  an ObjectNotFoundError. 
A)  a positive value 
B)  zero 
C)  a negative value 
D)  an ObjectNotFoundError.

Question 9

Which statement about hashing is false?

Accepted Answer

A)  Hashing facilitates high-speed storing and retrieval of data. 
B)  Two different data items can hash to the same cell; this is called a collision. 
C)  A load factor of 0.5 usually results in good hashing performance, but less efficient utilization of memory. 
D)  A load factor of 1.0 usually results in good hashing performance, but less efficient utilization of memory. 
A)  Hashing facilitates high-speed storing and retrieval of data. 
B)  Two different data items can hash to the same cell; this is called a collision. 
C)  A load factor of 0.5 usually results in good hashing performance, but less efficient utilization of memory. 
D)  A load factor of 1.0 usually results in good hashing performance, but less efficient utilization of memory.

Question 10

Class Collections provides algorithms for reversing, filling and copying ________.

Accepted Answer

A)  Lists. 
B)  Collections. 
C)  Arrays. 
D)  Stacks. 
A)  Lists. 
B)  Collections. 
C)  Arrays. 
D)  Stacks.

Question 11

Which of the following does not implement interface List?

Accepted Answer

A)  ArrayList. 
B)  LinkedList. 
C)  Vector. 
D)  ListIterator. 
A)  ArrayList. 
B)  LinkedList. 
C)  Vector. 
D)  ListIterator.

Question 12

A(n) __________ allows a program to walk through the collection and remove elements from the collection.

Accepted Answer

A)  Set. 
B)  Queue. 
C)  Iterator. 
D)  List. 
A)  Set. 
B)  Queue. 
C)  Iterator. 
D)  List.

Question 13

Which statement is false?

Accepted Answer

A)  A List is a Collection. 
B)  A List cannot contain duplicate elements. 
C)  A List is sometimes called a sequence. 
D)  Lists use zero-based indices. 
A)  A List is a Collection. 
B)  A List cannot contain duplicate elements. 
C)  A List is sometimes called a sequence. 
D)  Lists use zero-based indices.

Question 14

Maps allocate keys to values and cannot contain duplicate keys, i.e., the key-to-value mapping is a __________ mapping.

Accepted Answer

A)  many-to-many. 
B)  many-to-one. 
C)  one-to-many. 
D)  one-to-one. 
A)  many-to-many. 
B)  many-to-one. 
C)  one-to-many. 
D)  one-to-one.

Question 15

PriorityQueue method __________ inserts an element at the appropriate location in the queue.

Accepted Answer

A)  offer. 
B)  push. 
C)  poll. 
D)  peek. 
A)  offer. 
B)  push. 
C)  poll. 
D)  peek.

Question 16

Interface Collection contains __________ operations (i.e., operations performed on the entire collection).

Accepted Answer

A)  aggregate. 
B)  composite. 
C)  integral. 
D)  bulk. 
A)  aggregate. 
B)  composite. 
C)  integral. 
D)  bulk.

Question 17

Which statement is false?

Accepted Answer

A)  A ListIterator accesses the elements of a List. 
B)  Class ArrayList is a fixed-size array. 
C)  A LinkedList is a linked list implementation of a List. 
D)  ArrayLists execute faster than Vectors because they are not thread safe. 
A)  A ListIterator accesses the elements of a List. 
B)  Class ArrayList is a fixed-size array. 
C)  A LinkedList is a linked list implementation of a List. 
D)  ArrayLists execute faster than Vectors because they are not thread safe.

Question 18

Collections method ___________ returns a Comparator object that orders the collection's elements in reverse order.

Accepted Answer

A)  rotate. 
B)  shuffle. 
C)  reverse. 
D)  reverseOrder. 
A)  rotate. 
B)  shuffle. 
C)  reverse. 
D)  reverseOrder.

Question 19

Which statement is false?

Accepted Answer

A)  Java does not guarantee which item will be found first when a binarySearch is performed on a List containing multiple elements equivalent to the search key. 
B)  If the search key is found, method binarySearch returns the List index (position relative to 1) of the element containing the search key. 
C)  The binary search algorithm is fast. 
D)  Method binarySearch takes a List as the first argument. 
A)  Java does not guarantee which item will be found first when a binarySearch is performed on a List containing multiple elements equivalent to the search key. 
B)  If the search key is found, method binarySearch returns the List index (position relative to 1) of the element containing the search key. 
C)  The binary search algorithm is fast. 
D)  Method binarySearch takes a List as the first argument.

Question 20

Which of these is not an example of a "real-life" collection?

Accepted Answer

A)  The cards you hold in a card game. 
B)  Your favorite songs stored in your computer. 
C)  The players on a soccer team. 
D)  The number of pages in a book. 
A)  The cards you hold in a card game. 
B)  Your favorite songs stored in your computer. 
C)  The players on a soccer team. 
D)  The number of pages in a book.

Exam 16: Generic Collections

Collections method sort that accepts a List as an argument. It sorts the List elements, which must implement the __________ interface.

Comparator method compare should return ________ if the first argument is greater than the second argument.

Java supports type inferencing with the <> notation in statements that declare and create generic type variables and objects. For example, the following line: List<String> list = new ArrayList<String>(); Can be written as:

Stack method __________ looks at the top element of a stack without removing that element.

Which statement is false?

Which statement is false?

A Properties object is a __________ Hashtable object.

If the desired Object is not found, binarySearch returns __________.

Which statement about hashing is false?

Class Collections provides algorithms for reversing, filling and copying ________.

Which of the following does not implement interface List?

A(n) __________ allows a program to walk through the collection and remove elements from the collection.

Which statement is false?

Maps allocate keys to values and cannot contain duplicate keys, i.e., the key-to-value mapping is a __________ mapping.

PriorityQueue method __________ inserts an element at the appropriate location in the queue.

Interface Collection contains __________ operations (i.e., operations performed on the entire collection).

Which statement is false?

Collections method ___________ returns a Comparator object that orders the collection's elements in reverse order.

Which statement is false?

Which of these is not an example of a "real-life" collection?

Introduction to Computers and Java

Introduction to Java Applications

Control Statements

Control Statements

Methods

Arrays and Arraylists

Introduction to Classes and Objects

Classes and Objects: a Deeper Look

Object Oriented Programming: Inheritance

Object-Oriented Programming: Polymorphism

Exception Handling

Gui Components

Graphics and Java 2D

Fundamentals of Characters and Strings

Files, Streams and Object Serialization

Lambdas

Recursion

Searching, Sorting and Big O

Generic Classes and Methods

Custom Generic Data Structures

GUI

Concurrency

Accessing Databases With JDBC

JavaFX

Filters