CECS 277 Final Review
Aggregation
A 'has a' B relationship. B can exist without A.
Inheritance
A 'is-a' B relationship. Class B is derived from A.
Composition
A 'owns' B relationship. B cannot exist without A.
Dependency
A 'uses' B relationship.
Polymorphism
An object that can have multiple types.
Dynamic Binding
Create methods in superclass to override in the subclass
The keyword instanceof allows you to create an object of the type specified. (T/F)
False
When creating threads, you need to override the start() method. (T/F)
False
You should always add values to a BST in sorted order. (T/F)
False
A Vector is a type of set that allows you to preserve insertion order. (T/F)
False.
The ActionPerformed interface makes buttons clickable. (T/F)
False. ActionListener
Aggregation is the case where A 'has' B, and if A is destroyed, B is also destroyed. (T/F)
False. Aggregation = 'has a'. B can exist without A.
You need to close the scanner to save any changes to your file. (T/F)
False. Close the file.
Dependency is the case of A 'owns' B. (T/F)
False. Dependency = A 'uses' B
GUI stands for Global User Interface. (T/F)
False. It's GRAPHIC User Interface you nitwit.
To place an object into a HashSet, you are required to override compareTo() (T/F)
False. Override hashCode()
paintComponent() is used to place buttons and labels on your window. (T/F)
False. Panel is used to create and place buttons/labels
A map is used when uniqueness is required within your collection. (T/F)
False. Sets are used
Sorting algorithms that run at O(n^2) are faster than ones that are O(n log(n)). (T/F)
False. Speed of Big-O notation: O(1) - Constant O(long(n)) - Log O(n) - Linear O(n log(n)) - Log-Linear O(n^2) - Quadratic O(n^3) - Cubic O(2^n) - Exponential O(n!) - Factorial
Polymorphism is a variable of the subclass storing a reference to an object of the superclass. (T/F)
False. Superclass -> subclass
The List and Set interfaces extend the Collections interface. (T/F)
False. The List and Set interfaces IMPLEMENTS the Collections interface.
You can use a Scanner to write to a file. (T/F)
False. Use Printwriter
You can use a scanner to write to a text file. (T/F)
False. Use a Printwriter
Overriding
Methods with the same name as in its superclass
A FileInputStream reads bytes of data from a binary file. (T/F)
True
A Generic's type parameter is placed within angle brackets. (T/F)
True
A Heap keeps track of either the min or the max value at the root node. (T/F)
True
A method declared as abstract must be overriden. (T/F)
True
A polymorphic object cannot call methods of the subclass unless they are overridden. (T/F)
True
A subclass is extended from the superclass (T/F)
True
A try/catch block allows you to handle run time errors. (T/F)
True
All methods defined in an interface are automatically abstract. (T/F)
True
An abstract method is defined but not created. (T/F)
True
Any objects that will be sorted should implement Comparable. (T/F)
True
Binary Streams read and write single bytes to a file. (T/F)
True
Classes are made up of instance variables and methods. (T/F)
True
Dynamic binding makes methods in the superclass to override in the subclass. (T/F)
True
Encapsulation allows you to protect code and help make it reusable. (T/F)
True
IO streams are used to send messages between the Server and the Client. (T/F)
True
In a Map, all keys are unique. (T/F)
True
Multiple threads can share access to the same resources. (T/F)
True
Polymorphism is the term to describe when a variable is the data type of the superclass, but stores an object of the subclass. (T/F)
True
Serializable must be implemented in order to write an object to a binary file. (T/F)
True
Sockets are the means by which the Client and the Server are connected. (T/F)
True
The Collections class is a set of static methods for use on types of collections. (T/F)
True
The method drawString allows you to draw text on the window. (T/F)
True
Use the keyword 'extends' to inherit all data members and methods from the superclass to the subclass. (T/F)
True
When creating a new HashMap, you must specify two type arguments in <>. (T/F)
True
You can create objects from a class defined as final. (T/F)
True
You can create threads by extending Thread or implementing Runnable. (T/F)
True
You can use a scanner to read from a text file. (T/F)
True
You cannot create objects from a class declared as abstract. (T/F)
True
You must close a file when you are finished writing to it to save the changes. (T/F)
True
Interface
Specifies a behavior for a class.
If two different objects both hash to the same location, it is known as a __________. a. crash b. collision c. conflict d. clash
b. collision
Using a HashMap requires you to override the ______ method. a. compareTo() b. hashCode() c. comparable() d. getHash()
b. hashCode()
For a class to use an interface, it must use the keyword ________ a. extends b. implements c. interfaces d. references
b. implements
Lists are used when ___________ is (are) needed. a. hash codes b. indexing c. a key-value pair d. unique elements
b. indexing
The sleep method takes in the number of _____ it will sleep for. a. seconds b. milliseconds c. kiloseconds d. microseconds
b. milliseconds
Methods of an interface must be _______. a. inherited b. overriden c. downcasted d. dynamically bound
b. overriden
All methods in an interface are automatically created as _____ and ______. a. public, static b. public, abstract c. private, static d. private, abstract
b. public, abstract
A wildcard type can be constrained with a lower bound using the keyword _______. a. implements b. super c. constrain d. extends
b. super
Each node in a BST can have at most _____ child(ren). a. zero b. two c. one d. three
b. two
The symbol used for a wildcard is ______. a. # b. $ c. ? d. &
c. ?
If classes Dog and Cat extend abstract class Animal, which of the following will compile? a. Animal a = new Animal(); b. Dog d = new Animal (); c. Animal a = new Dog(); d. Cat c = new Animal();
c. Animal a = new Dog();
A class that extends ______ creates a window where components can be placed. a. AWT b. Swing c. JFrame d. JWindow
c. JFrame
To detect mouse clicks, the interface _____ must be implemented in the class. a. MouseMotionListener b. MousePressed c. MouseListener d. MouseClicked
c. MouseListener
Which interface needs to be implemented so an object of that class can be written to a file? a. Streamable b. Objectable c. Serializable d. Writable
c. Serializable
Maps are used when _______ is (are) needed. a. hash codes b. indexing c. a key-value pair d. unique elements
c. a key-value pair
Classes are used as a blueprint to make ______ of that type. a. methods b. statics c. objects d. variables
c. objects
A class extends ______ class(es), and implements ______ interface(s). a. zero to one, one to many b. zero to many, zero to one c. zero to one, zero to many d. zero to many, one to many
c. zero to one, zero to many
Using a TreeSet requires you to override the _____ method. a. compareTo() b. hashCode() c. comparable() d. getHash()
a. compareTo()
When one class inherits from another it must use the keyword _______. a. extends b. inherits c. abstract d. using
a. extends
To test the type of an object, you may use the keyword ______ a. instanceof b. getInstance c. classType d. getType
a. instanceof
Which of the following describes an 'Aggregation' relationship? a. 'is a' b. 'part of a' c. 'uses a' d. 'has a'
d. 'has a'
A ______ is used to receive a data stream. a. ServerSocket b. PrintStream c. Socket d. BufferedReader
d. BufferedReader
When constructing a PrintWriter, you must handle a _________ exception. a. UnknownFile b. NonExistantFile c. FileIO d. FileNotFound
d. FileNotFound
Which of the following is necessary to write an object to a binary file? a. ObjectReader b. ObjectSTream c. ObjectOutputReader d. ObjectOutputStream
d. ObjectOutputStream
To read from a text file, you need to declare a ______ first. a. Buffer b. Reader c. InputerFile d. Scanner
d. Scanner
The function _____ calls a thread's run method. a. wait() b. sleep() c. join() d. start()
d. start()
Sets are used when ______ is (are) needed. a. hash codes b. indexing c. a key-value pair d. unique elements
d. unique elements
A class may not use multiple generic type. (T/F)
False
A final class can be inherited. (T/F)
False
A method declared as final must be overriden. (T/F)
False
A networked connection cannot be multithreaded. (T/F)
False
A superclass is inherited from a subclass. (T/F)
False
A try/catch block cannot handle more than one type of exception at a time. (T/F)
False
BSTs always remove from the root. (T/F)
False
Generic methods may use a wildcard when passing in an unknown type. (T/F)
False
Methods can use the keyword 'locked' so only one thread can enter at a time. (T/F)
False
Private members of the superclass are accessible by the subclass. (T/F)
False
Final
This type of class cannot be inherited.
Abstract
This type of class cannot create objects.
Downcast
Typecasting an object as the subclass type.
A Server program allows incoming connections through a _______. a. ServerSocket b. PrintStream c. Socket d. BufferedReader
a. ServerSocket
To do File I/O, your program requires a ______ handler. a. FileReaderError b. FileNotFoundException c. FileExceptionError d. FileIOException
b. FileNotFoundException
A _______ is used to send a data stream. a. ServerSocket b. PrintStream c. Socket d. BufferedReader
b. PrintStream