Deck 16: Collections,maps,and Iterators

Question 1

To change an existing element of a vector you must use the __________ method.

A)add)
B)set)
C)change)
D)mutate)

Answer 1

B

Question 2

If you want a class that implements the Map interface and do not need any methods beyond those in the Map interface,you can use the ____________ class.

A)Vector< T >
B)AbstractMap< K,V >
C)HashMap< K,V >
D)HashSet< T >

Answer 2

C

Question 3

The Collection class or interface that allows only unique elements is the ___________ class or interface.

A)List< T >
B)Set< T >
C)Vector< T >
D)all of the above

Answer 3

B

Question 4

If you do not need efficient random access but need to efficiently move sequentially through the list,then use the _____________ class.

A)Vector< T >
B)LinkedList< T >
C)HashSet< T >
D)TreeSet< T >

Question 5

All of the following are methods of the Iterator interface except:

A)clear)
B)hasNext)
C)next)
D)remove)

Question 6

The primary interface/interfaces for a collection class is/are:

A)Collection< T >
B)Set< T >
C)List< T >
D)All of the above

Question 7

If you want a class that implements the List interface and do not need any methods beyond those in the List interface,you can use the ____________ class.

A)Vector< T >
B)LinkedList< T >
C)HashSet< T >
D)TreeSet< T >

Question 8

A Java collection is any class that implements the Collection interface.

Question 9

A collection is a data structure for holding elements.

Question 10

All of the following are members of Java's Collection class except:

A)Queue< T >
B)LinkedList< T >
C)Vector< T >
D)Set< T >

Question 11

The method ___________ can be used to determine the number of elements in an ArrayList.

A)length)
B)vectorLength)
C)size)
D)vectorSize)

Question 12

A ___________ is used to specify a wide range of parameters.

A)Collection
B)Iterator
C)Vector
D)Wildcard

Question 13

The interface SortedSet and the concrete class _________ is designed for implementations of the Set interface that provide for rapid retrieval of elements.

A)Vector< T >
B)LinkedList< T >
C)HashSet< T >
D)TreeSet< T >

Question 14

The hasNext)method of the Iterator interface has a return value of:

A)byte
B)int
C)boolean
D)none of the above

Question 15

A ____________ is a data structure for holding elements.

A)Collection
B)Iterator
C)Vector
D)Wildcard

Question 16

All of the following methods are part of the Collection< T > interface except:

A)Contains)
B)toArray)
C)retainAll)
D)toString)

Question 17

To use Java's Vector class,you must import the ___________ package.

A)java.Math
B)java.Exception
C)java.util
D)java.lang

Question 18

The method containsObject o)of the ArrayList class returns a value of type:

A)int
B)char
C)byte
D)boolean

Question 19

Memory management methods of the vector class include all of the following except:

A)remove)
B)trimToSize)
C)capacity)
D)size)

Question 20

If you want a class that implements the Set interface and do not need any methods beyond those in the Set interface,you can use the concrete class:

A)Vector< T >
B)LinkedList< T >
C)HashSet< T >
D)TreeSet< T >

Question 21

Elements of a vector must be of a primitive type,such as int,double,or char.

Question 22

An Iterator is an object that allows your code to produce the elements in a vector or other container one after the other,exactly once.

Question 23

For-each loops can not be used with Collection classes.

Question 24

What must you do before adding a primitive type to a vector?

Question 25

What is the difference between a vector's size and a vector's capacity?

Question 26

All Collection classes are part of the java.util package.

Question 27

Write a Java statement to recover the unused memory in the resulting vector in number 4 above.

Question 28

The number of entries that may be added to a HashMap< K,V > object is limited to what is specified as the initial capacity in the constructor for the HashMap< K,V > object.

Question 29

Write a Java statement to create a vector with initial capacity of 50.

Question 30

Write a Java statement that changes the value of element 27 to 5.0 in the resulting vector in number 3 above.

Question 31

< T > is a wildcard used to specify a wide range of parameters.

Question 32

The AbstractSequentialList class provides efficient implementation of sequentially moving through the list at the expense of having inefficient implementation of random access to elements.

Question 33

The List interface is for collections that allow repetition of elements and do not impose an order on their elements.

Question 34

Classes that implement the Set interface allows duplicate elements to occur.

Question 35

The difference between the List< T > interface and the Set< T > interface is that the Set< T > interface does not impose an order on its unique elements.

Question 36

The V parameter in a HashMap< K,V > may be any object,but the K parameter must be a String.

Question 37

A vector can potentially encounter an ArrayIndexOutOfBoundsException.

Question 38

Create a for loop to initially set the values of the vector created in number 1 above to the value of negative 1.0.

Question 39

Write a Java statement to resize the resulting vector in number 2 above to 100.

Question 40

When an interface lists a method as "optional," you do not need to implement it when defining a class that implements the interface.

Question 41

Write a method named displayList)that has one parameter of type Vector and has a return value of void.The method uses an iterator to display the contents of the Vector.

Question 42

Compare and contrast vectors and arrays.

Question 43

How can one retrieve all the values of a HashMap object?

Question 44

What is the purpose of the Java Iterator interface?