5 points QUESTION 2 What would be the best description of polymorphism. A java o
ID: 3831197 • Letter: 5
Question
5 points
QUESTION 2
What would be the best description of polymorphism.
A java object that can be attached to or refer to more than one class.
An object that refers to its parent.
An object that refers to itself.
Downcasting.
5 points
QUESTION 3
Java Swing classes allow for text components to be read only via what method?
setReadOnly()
setEditable()
setEditOnly()
setTextReadOnly()
5 points
QUESTION 4
A constructor is a special kind of method within a class having the following features:
1) the name of the method is the same as the class name
2) it does not have any return type not even void
3) like other methods, constructors can also be overloaded
Choose the correct assumption(s) from the listing above.
Only assumption 1 is correct.
Assumptions 1 & 2 are correct
None are correct.
All assumptions are good.
5 points
QUESTION 5
When creating a jar file (for executing a java program for a user) you can only choose one file in your package that has main().
True
False
5 points
QUESTION 6
Which of the following is true about protected access?
Protected members cannot be accessed by methods in any other classes.
Protected members may be accessed by methods in the same package or in a subclass, but only if the subclass is in the same package.
Protected members may be accessed by methods in the same package or in a subclass, even when the subclass is in a different package.
Protected members are actually named constants.
5 points
QUESTION 7
In the following code, System.out.println(num), is an example of ________.
double num = 5.4;
System.out.println(num);
num = 0.0;
A value-returning method
A local variable
A complex method
A void method
5 points
QUESTION 8
A column in one table that references a primary key in another table is known as what?
referential key
secondary key
foreign key
meta data
5 points
QUESTION 9
Which is not a solid example of encapsulation?
A Car class having a has-a relation with class Parts
Taking for granted a wikipedia definition
A washing machine and its use of a power Button
java.util.Hashtable
5 points
QUESTION 10
Given the depiction below, the relation of Song to Artist is one to one.
True
False
5 points
QUESTION 11
To convert the double variable, d = 543.98, to a string, use the following statement.
String str = Double.toString(d);
String str = d.Double.toString(str);
String str = double.toString(d);
String str = double(d);
5 points
QUESTION 12
An abstract class is not instantiated, but serves as a superclass for other classes.
True
False
5 points
QUESTION 13
For an optimal OOD design it is best to have
classes that are tightly coupled with high cohesion
classes that are loosely coupled with low cohesion
classes that are tightly coupled with low cohesion
classes that are loosely coupled with high cohesion
5 points
QUESTION 14
A search algorithm
Arranges elements in ascending order
Arranges elements in descending order
Is a way to locate a specific item in a larger collection of data
Is rarely used with arrays
5 points
QUESTION 15
In an interface all methods have
private access
public access
protected access
packaged access
5 points
QUESTION 16
Given the generic method below, what data types can be passed in?
public static
void displayArray(E[ ] array) {
for (E element : array)
::
}
any data type
any reference type
any data type that is a sub class of Number
any type that a super class of Number
5 points
QUESTION 17
The following statement creates an ArrayList object. What is the purpose of the notation?
ArrayList arr = new ArrayList<>();
It specifies that everything stored in the ArrayList object will be converted to a String
It specifies that only String objects may be stored in the ArrayList object
Nothing as the statement is invalid.
It specifies that the get method will return only String objects
5 points
QUESTION 18
The String[] args parameter in the main method header allows the program to receive arguments from the operating system command-line.
True
False
5 points
QUESTION 19
In a class hierarchy
the more general classes are toward the left of the tree and the more specialized are toward the right
the more general classes are toward the bottom of the tree and the more specialized are toward the top
the more general classes are toward the top of the tree and the more specialized are toward the bottom
the more general classes are toward the right of the tree and the more specialized are toward the left
5 points
QUESTION 20
Which of the following correctly tests the char variable chr to determine whether it is not equal to the character B?
if (chr < 'B')
if (chr != "B")
if (chr != 'B')
if (chr > 'B')
5 points
QUESTION 21
The three major categories of Java collections are
tree sets, list sets, and hash maps
lists, sets, and maps
hash lists, hash tables, and sets
sets, collections, and maps
5 points
QUESTION 22
Given that String[] str has been initialized, to get a copy of str[0] with all characters converted to upper case, use the following statement
str.uppercase();
str[0].toUpperCase();
str.toUpperCase();
str[0].upperCase();
5 points
QUESTION 23
What would be the results of the following code?
final int SIZE = 25;
int[] array1 = new int[SIZE];
... // Code that will put values in array1
int value = 0;
for (int a = 0; a <= array1.length; a++)
{
value += array1[a];
}
value contains the lowest value in array1
value contains the sum of all the values in array1
value contains the highest value in array1
This would cause the program to crash.
5 points
QUESTION 24
What is the value of str after the following code has been executed?
String str;
String sourceStr = "Hey diddle, diddle, the cat and the fiddle";
str = sourceStr.substring(12,17);
Iddle
diddl
diddle
, didd
5 points
QUESTION 25
If a subclass constructor does not explicitly call a superclass constructor,
The superclass fields will be set to the default values for their data types
It must include the code necessary to initialize the superclass fields
Java will automatically call the superclass's default constructor just before the code in the subclass's constructor executes
Java will automatically call the superclass's default constructor immediately after the code in the subclass's constructor executes
5 points
QUESTION 26
What term refers to data that describes other data?
meta data
pseudo-data
micro data
abstract data
5 points
QUESTION 27
If a class contains an abstract method,
The method must be overridden in subclasses
You cannot create an instance of the class
The method will have only a header, but not a body, and end with a semicolon
All of the above
5 points
QUESTION 28
In the following code, System.out.println(num), is an example of ________.
double num = 5.4;
System.out.println(num);
num = 0.0;
A value-returning method
A local variable
A complex method
A void method
5 points
QUESTION 29
In the realm of JDBC use of PreparedStatements help prevent what?
SQL Injection
increased threads
does not prevent anything, just executes insert statements like JDBC statements do
execution of stored procedures
5 points
QUESTION 30
If a subclass constructor does not explicitly call a superclass constructor,
It must include the code necessary to initialize the superclass fields
The superclass fields will be set to the default values for their data types
Java will automatically call the superclass's default constructor just before the code in the subclass's constructor executes
Java will automatically call the superclass's default constructor immediately after the code in the subclass's constructor executes
5 points
QUESTION 31
Given:
public class MyPancake implements Pancake {
public static void main(String[] args) {
List x = new ArrayList();
x.add("3"); x.add("7"); x.add("5");
List y = new MyPancake().doStuff(x);
y.add("1");
System.out.println(x);
}
List doStuff(List z) {
z.add("9");
return z;
}
}
interface Pancake {
List doStuff(List s);
}
What is the most likely result?
An exception is thrown at runtime
Compilation fails
[3, 7, 5, 9, 1]
[3, 7, 5]
[3, 7, 5, 9]
5 points
QUESTION 32
Assume q passed into the function below is: q={10,9,8,7,6,5,4,3,2,1}
What would be the resulting stack (st) at the line below with the comment labeled //1.____
public Queue interChanger(Queue q){
Stack st = new Stack();
int size = q.size()/2;
for(int i = 1; i <= size; i++){
st.push(q.remove()); //1. ____________
}
while(!st.isEmpty()){
q.add(st.pop()); //2. ____________
}
for(int i = 1; i <= size; i++){
q.add(q.remove()); //3. ____________
}
for(int i = 1; i <= size; i++){
st.push(q.remove()); //4. ____________
}
while(!st.isEmpty()){
q.add(st.pop());
q.add(q.remove()); //5. ____________
}
return q;
}
12345
54321
678910
109876
5 points
QUESTION 33
A major problem when classes are tightly coupled may be when what occurs?
When functions using local variables change the variables unexpectedly
When global variables that are in use and cause havoc perhaps upon any changes to them
When the constructor of a class no longer can rely on changes to the class variables
upon instantiation being unchanged
Tightly coupled classes are actually very beneficial and recommended to be coded in that fashion.
5 points
QUESTION 34
As a programmer we should try to
balance between tightly and loosely coupled classes.
minimize the use of coupling relations of classes
maximize the use of any coupling relations of classes
only allow tight coupling when changes need to be made to classes for maintenance purposes.
5 points
QUESTION 35
Given the Regex expression:
^[a-z0-9_-]{3,15}
and a string to compare against the expression such as
tom-thumbtomthumb
a match would be
tom
tom-
tom-thumbtomthu
tom-thumbtomthumb
5 points
QUESTION 36
What would be the results of executing the following code?
StringBuilder str = new StringBuilder(12);
str.append("The cow");
str.append(" jumped over the ");
str.append("moon.");
variable str would equal "The cow jump"
variable str would equal "The cow jumped over the"
variable str would equal "The cow jumped over the moon."
The program would crash.
5 points
QUESTION 37
Given the ages for object creations for class AgeGroups as 33,22,44,55 respectively, what would the following Comparator declaration return for each age outcome order?
Collections.sort(listDevs, new Comparator() {
@Override
public int compare(AgeGroups o1, AgeGroups o2) {
return -o1.getAge() ;
}
});
33,22,44,55
55,44,22,33
22,33,44,55
order would be random
5 points
QUESTION 38
An abstract class cannot be instantiated primarily because
any of the class attributes cannot be modified
subclasses should only be allowed to implement the desired behaviors associated with the abstract class its inheriting from
methods may choose to be overriding any behaviors that may be declared abstract by the inherited abstract class
too much memory would be allocated for both the super (abstract) class and any of its decendents.
5 points
QUESTION 39
In the following code, assume that inputFile references a Scanner object that has been successfully used to open a file:
double totalIncome = 0.0;
while (inputFile.hasNext())
{
try
{
totalIncome += inputFile.nextDouble();
}
catch(InputMismatchException e)
{
System.out.println("Non-numeric data encountered " +
"in the file.");
inputFile.nextLine();
}
finally
{
totalIncome = 35.5;
}
}
What will be the value of totalIncome after the following values are read from the file?
2.5
8.5
3.0
5.5
abc
1.0
0.0
19.5
75.0
35.5
5 points
QUESTION 40
In an interface all methods have
private access
public access
packaged access
protected access
A java object that can be attached to or refer to more than one class.
An object that refers to its parent.
An object that refers to itself.
Downcasting.
Artist Performs SongExplanation / Answer
Question 2:
========
Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object.
Question 4:
=======
Assumptions 1 and 2 are correct.
A constructor is a special kind of subroutine in a class. It has the same name as the name of the class, and it has no return type, not even void.
Question 3:
=======
The java.io.File.setReadOnly() method switches the file to read only mode and denies any write operations on the file.
Question 5:
=======
True.Need to specify a Main-Class in the jar file manifest.
Question 6:
=======
Protected members cannot be accessed by methods in any other classes.
Protected members may be accessed by methods in the same package or in a subclass, but only if the subclass is in the same package.
Question 7:
=======
Local Variable
Question 8:
=======
Foreign Key.
Question 9:
=======
A washing machine and its use of a power Button
Question 10:
=======
True.
Q 11:
===
String str = Double.toString(d);
Q 12:
===
True.
Q 13
===
Generally, good OO design should be loosely coupled and highly cohesive. Lot of the design principles, design patterns which have been created are based on the idea of “Loose coupling and high cohesion”.
Q 14:
====
A search algorithm is a method of locating a specific item in a larger collection of data
Q 15:
===
In an interface all methods have publc access
Q 17:
===
It specifies that only String objects may be stored in the ArrayList object.
Q 18:
===
True
Q 19:
===
the more general classes are toward the top of the tree and the more specialized are toward the bottom
Q 20:
===
if (chr != 'B')
Q 21:
===
sets, collections, and maps
Q 22:
===
str.toUpperCase();
Q 24:
===
Q 26:
====
meta data
Q 28:
====
local variable
Q 29:
===
SQL Injection
Q 36:
===
The program would crash.
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