Java Final Unit
True or false? The constructor of a subclass specifies a call to the constructor of the superclass using the name of the class.
false
True or false? The order in which catch blocks are listed is not important
false
True or false? Making a reference to an object that has not yet been instantiated would throw an exception from the NullPointerException class
true
True or false? On average, a sequential search searches half the list.
true
True or false? One way to handle an exception is to print an error message and exit the program
true
True or false? Selection sort swaps the smallest element in the unsorted portion of the list to a new position.
true
True or false? The block finally is always executed
true
True or false? The length of a list is the number of elements in the list.
true
True or false? The process of solving a problem by reducing it to smaller versions of itself is called recursion
true
True or false? To design a recursive method, you must determine the limiting conditions
true
True or false? A syntax error will result if the control statements of a for loop are omitted
False
True or false? Including a semicolon before the action statement in a one way selection causes a syntax error
False
After completing a particular recursive call, control goes back to the ___ ___
calling environment (which is the previous call)
A subclass can/cannot override the methods of a superclass
can
An abstract class can/cannot contain an abstract method(s)
can
The ___ of a catch block specifies the type of exception it handles
heading
A(n) ___ is a class that contains only abstract methods and/or named constants
interface
An ___is a class that contains only abstract methods and/or named constants
interface
Java allows a class to implement more than one ___. This is, in fact, the way to implement a form of multiple inheritance in Java
interface
Inheritance is an example of what type of relationship? a) is-a b) has-a c) was-a d) had-a
is-a
The classes to deal with number format exceptions and arithmetic exceptions such as division by zero are contained in the package ___
java.lang
The class InputMismatchException is contained in the package ___
java.util
Except for a few special cases, Java uses ___ binding for all methods
late
In ___ ___ a method's definition is associated with its invocation at execution time, that is, when the method is executed
late binding
A ___ is a set of elements of the same type.
list
True or False? An abstract method is a method that has only the heading with no body.
true
True or False? If a class is declared final, then no other class can be derived from this class.
true
True or False? In Java, polymorphism is implemented using late binding.
true
True or False? In multiple inheritance, the subclass is derived from more than one superclass.
true
True or False? The class Object is directly or indirectly the superclass of every class in Java.
true
True or false? To determine whether a given item is in an ordered list of length 1024, binary search makes at most 22 key comparisons.
true ( 2 * log base 2 of n = 22 when n is 1024)
Action events are handled by appropriately implementing the interface ___
ActionListener
If a negative value is used for an array index, what exception is thrown?
ArrayIndexOutOfBoundsException
The class Throwable is the superclass of the class ___
Exception
The class ___ is the superclass of the classes designed to handle exceptions
Exception
The class ___and its subclasses are designed to catch exceptions that should be caught and processed during program execution, and thus make a program more robust.
Exception
The exception class that you define extends the class ___ or one of its subclasses
Exception
The class FileReader is derived from the class ___
InputStreamReader
What happens in a method if there is an exception thrown in a try block but there is no catch block following the try block? a) The program ignores the exception. b) The program will not compile without a complete try/catch structure. c) The program terminates immediately. d) The program throws an exception and proceeds to execute the finally block.
The program throws an exception and proceeds to execute the finally block
The class ___ implements the interface WindowListener by providing empty bodies to the methods
WindowAdapter
If you want to provide your own code to terminate the program when the window is closed, or if you want the program to take a different action when the window closes, then you use the interface ____. a) WindowListener b) ActionListener c) CloseListener d) MouseListener
WindowListener
The class PrinterWriter is derived from the class ___
Writer
A(n) ___ method is a method that has only the heading, not the body. Moreover, the heading of a(n) ___ method is terminated with a semicolon
abstract
An abstract class that is declared with the reserved word ___ in its heading
abstract
The ___ ___ stops the recursion
base case
In ___ ___ a method's definition is associated with its invocation when the code is compiled
early binding
Consider the following definition of a recursive method. public static int recFunc(int num) { if (num >= 10) return 10; else return num * recFunc(num + 1); } What is the output of the following statement? System.out.println(recFunc(10));
10
If this list was sorted using selection sort, which two elements would be swapped first? {16, 30, 24, 7, 25, 62, 45, 5, 65, 50}
16 and 5 (on first iteration of selection sort, index 0 is swapped with the smallest element of array)
If the following list was sorted, what would be the middle element? {16, 30, 24, 7, 25, 62, 45, 5, 65, 50}
25 ({5, 7, 16, 24, 25, 30, 45, 50, 62, 65}) (on canvas the answer is 24)
Consider the following list. list = {16, 30, 24, 7, 25, 62, 45, 5, 65, 50}; Suppose that sequential search is used to determine whether 24 is in list. Exactly how many key comparisons are executed by the sequential search algorithm?
3 (sequential search makes key comparisons one by one down the list, 24 is the 3rd element)
If a binary search was used on this list, which element would the search element be compared to first? {4, 18, 29, 35, 44, 59, 65, 98}
35 (binary search looks at the middle element first)
Consider the following list. list = {20, 10, 17, 2, 18, 35, 30, 90, 48, 47}; Suppose that sequential search is used to determine whether 2 is in list. Exactly how many key comparisons are executed by the sequential search algorithm?
4
public static int exampleRecursion (int n) { if (n == 0) return 0; else return exampleRecursion(n - 1) + n * n * n; } What is the output of exampleRecursion(3)? a) 25 b) 32 c) 36 d) 42
42 ( 3 cubed + 2 cubed + 1 cubed = 27 +8 + 1 =36 )
Consider the following definition of a recursive method. public static int recFunc(int num) { if (num >= 10) return 10; else return num * recFunc(num + 1); } What is the output of the following statement? System.out.println(recFunc(8)); a) 8 b) 72 c) 720 d) none
720 ( 8 * 9 * 10 = 720)
Key events are handled by appropriately implementing the interface ___
KeyListener
The class ___ implements the interface MouseListenerby providing empty bodies to the methods
MouseAdapter
Mouse events are handled by appropriately implementing the interface ___
MouseListener
The class RuntimeException is the superclass of which of the following classes? a) NullPointerException b) NoSuchMethodException c) IllegalAccessException d) NoSuchFileException
NullPointerException
Which of the following exceptions might be thrown by the methods of the class String? a) NullPointerException b) FileNotFoundException c) NoSuchElementsException d) NumberFormatException
NullPointerException
The Java classes Reader and Writer are derived from the class ____.
Object
The class Throwable is derived from the class ___
Object
The class ___ directly or indirectly becomes the superclass of every class in Java
Object
The classes Scanner, Reader, and Writer are derived from the class ___
Object
The class InputStreamReader is derived from the class ___
Reader
Which class of exceptions is NOT checked? a) FileNotFoundException b) ArithmeticException c) RuntimeException d) All exceptions are checked
RuntimeException
Consider the following definition of a recursive method. public static int foo(int n) //Line 1 { //Line 2 if (n == 0) //Line 3 return 0; //Line 4 else //Line 5 return n + foo(n - 1); //Line 6 } Which of the statements represent the base case? a) statements in lines 3 and 4 b) statements in lines 5 and 6 c) statements in lines 3, 4, and 5 d) none of these
Statements in lines 3 and 4
Window events are handled by appropriately implementing the interface ___
WindowListener
To register a mouse listener object to a GUI component, you use the method ___. The mouse listener object being registered is passed as a parameter to the method ___.
addMouseListener
To register a window listener object to a GUI component, you use the method ___. The window listener object being registered is passed as a parameter to the method ___.
addWindowListener
In Java, the mechanism that allows you to combine data and operations on the data into a single unit is called a(n) ____.
algorithm
When is a finally block executed? a) Only when an exception is thrown by a try block b) Only when there are no exceptions thrown c) At the end of a program d) Always after the execution of a try block, regardless of whether or not an exception is thrown
always after the execution of a try block, regardless of whether or not an exception is thrown
To run a Java application program, a program called a(n) ____ loads the .class file into computer memory.
assembler
Consider the following list. list = {24, 20, 10, 75, 70, 18, 60, 35} Suppose that list is sorted using the insertion sort algorithm. What is the resulting list after two passes of the sorting phase; that is, after three iterations of the for loop? (type in letter for corresponding answer) a) list = {10, 18, 20, 24, 75, 70, 60, 35} b) list = {10, 20, 24, 75, 70, 18, 60, 35} c) list = {10, 18, 20, 24, 35, 70, 60, 75} d) list = {10, 20, 20, 18, 35, 70, 60, 75}
b
If class Dog has a subclass Retriever, which of the following is true? (type in the letter of option choice) a) Because of single inheritance, Dog can have no other subclasses b) Because of single inheritance, Retriever can extend no other class except Dog c) The relationship between these classes implies that Dog "is-a" Retriever d) The relationship between these classes implies that Retriever "has-a" Dog
b
True or false? To design a recursive method, you must identify the ___ cases and provide a direct solution to each ___ case
base
The solution to a problem in a ___ ___ is obtained directly
base case
Consider the following list. list = {24, 20, 10, 75, 70, 18, 60, 35} Suppose that list is sorted using the selection sort algorithm. What is the resulting list after two passes of the sorting phase; that is, after two iterations of the outer for loop? (type in letter for corresponding answer) a) list = {10, 18, 24, 20, 75, 70, 60, 35} b) list = {10, 18, 20, 24, 75, 70, 60, 35} c) list = {10, 18, 24, 75, 70, 20, 60, 35} d) list = {10, 20, 24, 75, 70, 20, 60, 35}
c
An abstract class can/cannot contain instance variables, constructors, a finalizer, and nonabstract methods
can
An abstract class can/cannot be instantiated
cannot
You can/cannot automatically consider a superclass object to be an object of a subclass
cannot
You can/cannot automatically make a reference variable of a subclass type point to an object of a superclass type
cannot
An abstract class ____ a) does not have any subclasses b) is a superclass with many subclasses c) cannot be instantiated d) is the base class of all other classes
cannot be instantiated
A ___ block specifies the type of exception it can catch and contains an exception handler
catch
A try block is followed by zero or more ___ blocks
catch
Any exception that can be recognized by the compiler is called a ___ exception
checked
Java's predefined exceptions are divided into two categories: ___ and ___ exceptions
checked and unchecked
An exception that can be recognized by the compiler is a(n) ___
checked exception
What is the correct syntax for defining a new class Parakeet based on the superclass Bird?
class Parakeet extends Bird {} (class className extends superclassName {} )
In ___, one or more members of a class are objects of one or more other classes
composition (aggregation)
___ is a "has-a" relationship
composition (aggregation)
A method is ___ ___ if it calls itself
directly recursive
Generally, ___ classes are placed in the package that contains the methods that throw these exceptions
exceptions
If you define a class and do not use the reserved word ___ to derive it from an existing class, then the class you define is automatically considered to be derived from the class ___
extends, Object
A binary search is faster on ordered lists and slower on unordered lists
false
True or False? Interfaces are defined using the reserved word interface and the reserved word class.
false
True or False? Redefining a method of a superclass is also known as overloading a method
false
True or False? The private members of a superclass can be accessed by a subclass.
false
True or False? To override a public method of a superclass in a subclass, the corresponding method in the subclass must have the same name but a different number of parameters.
false
True or false? A GUI component can generate only one type of event
false
True or false? A binary search can be used on an unsorted list.
false
True or false? A list is a set of related values that do not necessarily have the same type.
false
True or false? A selection sort always starts with the middle element of the list
false
True or false? A sequential search is faster than a binary search on sorted lists.
false
True or false? A sequential search of a list assumes that the list is in ascending order
false
True or false? A subclass must define a constructor
false
True or false? All exceptions must be reported to avoid compilation errors
false
True or false? An unchecked exception is any exception that causes a program to terminate
false
True or false? On average, the number of comparisons made by a sequential search is equal to one-third the size of the list.
false
True or false? Suppose that you have the following list. int[] list = {1, 3, 5, 7, 9, 11, 13, 15, 17}; Further assume that binary search is used to determine whether 8 is in list. When the loop terminates, the value of the index variable first is 1.
false
True or false? The constructor of a subclass specifies a call to the constructor of the superclass in the heading of the constructor's definition.
false
True or false? The order in which catch blocks are placed in a program has no impact on which catch block is executed.
false
True or false? The try block contains statements that should be executed regardless of whether or not an exceptions occurs.
false
True or false? a recursive method always returns a value.
false
True or false? Java does not allow users to create and implement their own exception classes.
false (Java does allow users to create their own exception classes)
True or false? The general case stops the recursion.
false (base case is where the recursion stops)
True or false? In the general case, the solution to the problem is obtained directly.
false (base case is where the solution to the problem is obtained directly)
True or false? File not found is an unchecked exception
false (it is checked)
True or false? Division by zero is a checked exception
false (it is unchecked)
True or false? A binary search can be used on an unsorted list
false (it must be sorted for binary search)
True or false? Every recursive definition can have zero or more base cases
false (one or more base cases)
True or false? The methods getMessage and printStackTrace are private methods of the class Throwable.
false (they are Public methods of the class Throwable)
In general, a binary search is much ___ than a sequential search
faster
The code contained in the ___ block always executes, regardless of whether or not an exception occurs (except when the program exits early from a __ block by calling the method System.exit
finally
The last catch block may or may not be followed by a ___ block
finally
A sequential search algorithm searches the list for a given item, starting with the ___ element in the list.
first
The MouseListener interface defines how many methods?
five
True or false? To design a recursive method, you must identify the ___ case(s) and provide a solution to each ___ case in terms of a smaller version of itself
general
The ___ ___ must eventually be reduced to a base case
general case
The ___ ___ breaks a problem into smaller versions of itself
general solution
The method ___ returns the string containing the detailed message stored in the exception object.
getMessage
An abstract method ___ a) is any method in the abstract class b) cannot be inherited c) has no body d) is found in a subclass and overrides methods in a superclass using the reserved word abstract
has no body
A method that calls another method and eventually results in the original method call is ___ ___
indirectly recursive
___ is an "is-a" relationship
inheritance
The ___ ___ algorithm sorts the list by inserting each element in its proper place
insertion sort
The ___ operator is used to determine if an object is of a particular class type
instanceof
A method is recursive if it calls ___
itself
The classes to deal with I/O exceptions, such as the file not found exception, are contained in the package ___
java.io
The class Exception is contained in the package ___
java.lang
What are the three exception handling techniques?
log the error and continue, fix the error and continue, terminate the program (LFT)
In ___ ___, a subclass is derived from more than one superclass. Java does not support this. (in Java, a class can only extend the definition of one class)
multiple inheritance
An exception is a(n) ___ of a specific exception class
object
When an exception occurs an ___ of a specific exception class is created
object
Every recursive algorithm has ___ or more base cases
one
Every recursive definition has ___ or more base cases
one
Every recursive method must have ___ or more base cases
one
A ___ ___ ___ is a convenient data structure for storing and processing lists
one dimensional array
Consider the following class definitions. public class BClass { private int x; public void set(int a) { x = a; } public void print() { System.out.print(x); } } public class DClass extends BClass { private int y; public void set(int a, int b) { //Postcondition: x = a; y = b; } public void print(){ } } Which of the following correctly redefines the method print of DClass? (i) public void print() { System.out.print(x + " " + y); } (ii) public void print() { super.print(); System.out.print(" " + y); }
only ii
The term ___ means assigning multiple meanings to the same method. In Java, ___ is implemented using late binding
polymorphism
The method ____ is used to determine the order in which the methods were called and where the exception was handled
printStackTrace
The ___ members of a superclass are ___ to the superclass. The subclass cannot directly access them.
private
For a superclass to give direct access to its member(s), to its subclass(es), and still prevent its direct access outside the class, such as in a user program, you must declare that member using the modifier ___
protected
The methods getMessage, printStackTrace, and toString of the class Throwable are ___ and so ___ inherited by the subclasses of the class Throwable.
public, are
A ___ algorithm solves a problem by reducing it to smaller versions of itself
recursive
A ___ definition defines the problem in terms of smaller versions of itself
recursive
Recursive algorithms are implemented using ____ methods
recursive
Logically, you can think of a ___ ___ as having unlimited copies of itself
recursive method
A ___ ___ of a class can refer to either an object of its own class or an object of its subclass
reference variable
public static int exampleRecursion (int n) { if (n == 0) return 0; else return exampleRecursion(n - 1) + n * n * n; } What does the code in the code above do? a) returns the cube of the number n b) returns the sum of the cubes of the numbers, 0 to n c) returns three times the number n d) returns the next number in a fibonacci sequence
returns the sum of the cubes of the numbers, 0 to n
In a ___ ___ a list is sorted by selecting elements in the list, one at a time, and moving them to their proper positions
selection sort
This algorithm finds the location of the smallest element in the unsorted portion of the list and moves it to the top of the unsorted portion (i.e., the whole list) of the list.
selection sort
In ___ ___, the subclass is derived from only one existing class, called the superclass
single inheritance
What type of inheritance does Java support? a. single inheritance b. double inheritance c. multiple inheritance d. Java does not support inheritance
single inheritance
If the ___ does not override a public method of the superclass, you can specify a call to that public method by using the name of the method and an appropriate parameter list.
subclass
When a subclass overrides the method of a superclass, the redefinition is only available to objects of the ___
subclass
If the subclass overrides a public method of a superclass, then you specify a call to that public method of the superclass by using the reserved word ___, followed by the dot operator, followed by the method name with an appropriate parameter list
super
While writing the definition of a constructor of a subclass, a call to a constructor of the superclass is specified using the reserved word ___ with an appropriate parameter list. (the call to a constructor of the superclass must be the first statement)
super
A recursive method in which the last statement executed is the recursive call is called a ___ ___ ___
tail recursive method (TRM)
Which operator is used to determine if an object is of a particular class type? a) The operator new b) The dot(.) operator c) The instanceof operator d) The + operator
the instanceof operator
Consider the following class definitions. public class BClass { private int x; private double y; public void print() { } } public class DClass extends BClass { private int a; private int b; public void print() { } } Suppose that you have the following statement. DClass dObject = new DClass(); How many instance variables does dObject have?
three
Which of the following is NOT a method of the class Throwable? a) getMessage b) throwMessage c) printStackTrace d) toString
throwMessage
The method ___ (in class Exception) returns the detailed message stored in the exception object as well as the name of the exception class.
toString
A binary search of a list assumes that the list is in sorted order
true
True or False? To determine whether a reference variable that points to an object is of a particular class type, Java provides the operator instanceof.
true
True or false? A catch block can catch either all exceptions of a specific type or all types of exceptions
true
True or false? A reference variable of a superclass type can point to an object of a subclass type
true
True or false? An abstract method has no body.
true
True or false? An event handler is a method
true
True or false? An exception can be caught either in the method where it occurred or in any one of the methods that led to the invocation of this method
true
True or false? During program execution, if division by zero occurs with integer values and is not addressed by the program, then the program terminates with an error message indicating an attempt to divide by zero.
true
True or false? Every recursive definition must have one or more base cases.
true
True or false? Every recursive method must have one or more base cases.
true
True or false? Exceptions are thrown either in a try block in a method or from a method called directly or indirectly from a try block
true
True or false? If a class contains an abstract method, then the class must be declared abstract
true
True or false? If a try block is not followed by a catch block, then it must have a finally block.
true
True or false? If an exception occurs in a try block and that exception is caught by a catch block, then the remaining catch blocks associated with that try block are ignored.
true
True or false? In Java, polymorphism is implemented using late binding
true
True or false? In a class hierarchy several methods can have the same name and the same formal parameter list
true
True or false? Java provides extensive support for exception handling by providing several exception classes.
true
True or false? To design a recursive method, you must understand the problem requirements
true
True or false? To handle window events, you first create a class that implements the interface WindowListener and then create and register objects of that class
true
True or false? When an exception occurs in a method, you can use the method printStackTrace to determine the order in which the methods were called and where the exception was handled.
true
True or false? You can instantiate an object of a subclass of an abstract class, but only if the subclass gives the definitions of all the abstract methods of the superclass
true
True or false? You cannot instantiate an object of an abstract class. You can only declare a reference variable of an abstract class type
true
The ___ block contains statements that should not be executed if an exception occurs
try
statements that may generate an exception are placed in a ___ block
try
the ___ / ___ / ___ block is used to handle exceptions within a program
try catch finally (TCF)
How many constructors does the class Exception have?
two
Inheritance and composition(aggregation) are meaningful ways to relate ___ or more classes
two
The class Exception contains ___ constructors.
two
___ exceptions are exceptions that are not recognized by the compiler
unchecked
