Exam 2 CIS 315
Which is the only method specified by the Runnable interface?
run
Which Thread method requires a specified amount of time as input?
sleep
Your application must extend the Application class and implement which abstract method?
start
A recursive method should have a "base case". Which of the following is synonym for "base case"?
stopping condition
Which keyword should you use in the method header (just before the return type) to ensure that only one thread executes the method body at any one time?
synchronized
?
unbounded wildcard
Which Thread method temporarily releases an arbitrary amount of time for other threads to execute?
yield
All recursive methods have the following characteristics (Select all that apply, type numbers only spaces) 1. uses if-else or switch that leads to different cases. 2. one or more base cases 3. each recursive call reduces the original problem 4. have a void return type
1 2 3
To create a Socket object (which represents a communication endpoint), which two pieces of information are required by the Socket class constructor? (type number) 1. hostname or IP address 2. operating system 3. timeout parameter 4. port number
1 4
When two keys are mapped to the same index in a hash table, this is called: Double hashing A collision Linear probing Rehashing
A collision
A marker interface is: An unused interface An abstract interface An interface with an empty body An interface with a full implementation
An interface with an empty body
Generics: (select all that apply) Are any important part of the API of collection classes (like ArrayList). Have been part of Java since the beginning (JDK 1.0). Let you parameterize types. help detect errors at compile time, instead of runtime.
Are any important part of the API of collection classes (like ArrayList). Let you parameterize types. help detect errors at compile time, instead of runtime
Vector is most similar to which newer collection class? Stack Queue ArrayList Iterator
ArrayList
Which is the best data structure for storing a graph? HashSet HashMap TreeMap LinkedHashSet ArrayList
ArrayList
Which class(es) implement the List interface? ArrayList LinkedList PriorityQueue TreeSet
ArrayList and LinkedList
Which of the following is an abstract class? GregorianCalendar, java.util.date, Calendar, or ArrayList
Calendar
To sort and search collections you should use which class that contains mostly static methods? Math Collection Arrays Collections
Collections
Which class supports red, green, and blue values?
Color
O(1)
Constant time
An interface is a class-like construct that contains only: (Select all that Apply) Fields Constants Methods Abstract Methods
Constants and Abstract methods
A graph consists of _______ and ______ Sets Edges Lists Vertices Weights
Edges and Vertices
O(2^n)
Exponential time
A _____ is a mixture of JSF tags and XHTML tags.
Facelet
A JavaBean is written in HTML
False
A class may extend multiple abstract classes. T or F
False
An abstract class must have at least one method that is marked abstract. T or F
False
If you need to maintain insertion order in your map, you should use HashMap. True or False
False
Iteration takes more time and consumes more memory than recursion
False
JDBC was designed to work exclusively with Oracle databases.
False
Which class supports size and weight attribute values?
Font
Set
Group of nonduplicate elements
Which of the following are ways to traverse a tree? Inorder Preorder Postorder Backorder Depth-first Breadth-first
Inorder, Preorder, Postorder, Depth-first, Breadth-first
Which of the following are true of the Number class?(Select all that apply) It is abstract It is concrete It is a superclass of BigDecimal It is a subclass of BigDecimal It can be used as an object reference
It is abstract, It is a superclass of BigDecimal, It can be used as an object reference
What is the newest GUI framework supported by JAVA?
JavaFX
O(n)
Linear time
O(n log n)
Log-linear time
O(log n)
Logarithmic time
Which of these sorting algorithms is the most efficient? (consider the worst-case complexity) Selection sort Insertion sort Bubble sort Merge sort
Merge sort
JSF is based on which design pattern?
Model-View-Controller
Which Java keyword is used to indicate that the method is implemented in the JVM using code specific to the platform (i.e., operating system)? Native Transient Volatile Null
Native
What kind of performance can you expect from the search, insert, and delete operations of the typical hashtable? O(1) O(n) O(log n) O(n log n)
O(1)
Queue
Objects processed in FI-FO
Stack
Objects processed in LI-FO
PriorityQueue
Objects processed in order of priority
List
Ordered collection of elements
To lay out widgets with a desired size in a particular location, you would use a:
Pane
Precompiled for efficient use when repeatedly executed?
PreparedStatement
O(n^2)
Quadratic time
A generic class or interface without specifying a concrete type, called a ______ type, enables backward compatibility with earlier versions of Java. Object Abstract Primitive Raw
Raw
To send objects from one program to another using ObjectInputStream and ObjectOutputStream, the objects sent across the wire need to be instantiated from classes that implement which interface?
Runnable
Which of the following is the universal language for working with relational database systems
SQL
Which of the following are concrete classes? Map SortedMap NavigableMap TreeMap AbstractMap HashMap LinkedHashMap
TreeMap, HashMap, LinkedHashMap
Which of the following are concrete classes? Treeset Set SortedSet HashSet AbstractSet LinkedHashSet
TreeSet, HashSet, LinkedHashSet
A generic type can be defined for a class or interface. True or False
True
A subclass can be abstract even if its superclass is concrete. True or False
True
A tree is a graph. True or False
True
An O(log n) algorithm is more efficient than a O(n) algorithm. True or False
True
Assuming a BST with only a root node, if the next node to be added is less than the root, it should be added as the left child of the root. True or False
True
JavaServer Faces allows developers to separate HTML from Java code
True
Most database systems are relational database systems
True
One should try to make recursive methods use tail recursion to be more efficient
True
Sets are more efficient than lists for storing nonduplicate elements? True or False
True
Two equal objects (that produce a true return value when the equals method is called) must return the same hash code. True or False
True
You cannot use the new operator to instantiate an object from an abstract class. TorF
True
Which protocol guarantee lossless transmission and is therefore more suitable for audio and video than email?
UDP
Which data structure is the best choice for representing between cities? unweighted graph weighted graph TreeMap TreeSet
Weighted Graph
AVL trees are: Unary trees Degenerate trees Well-balanced trees Cyclic trees
Well-balanced trees
A server that uses a ServerSocket instance should listen for connections using which method?
accept
? extends T
bounded wildcard
________ checks whether the checkbox chk is selected.
chk.isSelected()
O(n^3)
cubic time
To implement your own hashing function in Java, you should override the ______ method which is defined in the Object Class
hashCode()
Java.util.Collection is a(n): Interface Abstract Class Final class class
interface
To set the node to the right of the text in a label lbl, use _______
lbl.setContentDisplay(ContentDisplay.RIGHT);
? super T
lower-bound wildcard
To create a label with the specified text, use _______
new Label(text);
To handle the key pressed event on a pane p, register the handler with p using ______
p.setOnKeyPressed(handler);
To handle the mouse click event on a pane p, register the handler with p using _____
p.setOnMouseClicked(handler);
