What is the primary purpose of multithreading in Java?

To allow multiple threads to run concurrently

Which of the following is a correct statement about inheritance in Java?

A class can inherit only from one class.

What is the primary purpose of an abstract class in Java?

To provide a common interface for its subclasses

What happens if an exception is not caught in a program?

The program terminates immediately.

Which of the following is NOT a characteristic of a daemon thread?

It prevents the JVM from shutting down

How do you initialize a 2D array with 3 rows and 4 columns?

int [] [] arr = new int[3] [4];

If a superclass method is private, can it be overridden by the subclass?

No, private methods cannot be overridden.

What will happen if two threads have the same priority?

The execution order will depend on the thread scheduler

Which of the following best describes polymorphism in object-oriented programming?

The ability of a variable, function, or object to take on multiple forms

Which of the following statements about arrays in Java is incorrect?

Arrays in Java are dynamically resizable.

Which of the following statements is true about abstract classes and interfaces in Java?

Abstract classes can implement methods; interfaces cannot

If a try block has multiple catch blocks, how many of them will be executed?

Only the first one that matches the exception type

What is the significance of the Thread.sleep(0) call?

immediately yield execution to other threads of the same priority

What is the correct syntax to catch multiple exceptions in Java?

catch (Exception1 | Exception2 e)

What is an abstract class in Java?

A class that cannot be instantiated

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Answers

1
What is the primary purpose of multithreading in Java?
To allow multiple processes to run in parallel
To allow multiple threads to run concurrently
To speed up the program execution
To simplify code debugging
2
Which of the following is a correct statement about inheritance in Java?
A class can inherit from multiple classes.
None of the above.
A class cannot inherit from another class.
A class can inherit only from one class.
3
Encapsulation can lead to which of the following?
Reduced readability
Low cohesion
Tight coupling
Better maintainability
4
Which class is the parent class of all the classes in java
Java
Parent
Object
Class
5
Which of the following is NOT a benefit of encapsulation?
Simplified maintenance
Increased security of data
Better control over data
Code reusability
6
Can a class in Java be both abstract and final?
Yes
Only if it does not have abstract methods
Only if it has private constructors
No
7
What is the primary purpose of an abstract class in Java?
To instantiate objects directly
To prevent inheritance
To provide a common interface for its subclasses
To define global constants
8
What happens if an exception is not caught in a program?
The program terminates immediately.
The program continues normally.
The program waits for the user to handle it.
The program throws a NullPointerException.
9
When a string is created using the new keyword, where is it stored?
Stack memory
Method area
String pool
Heap memory
10
Which of the following is NOT a characteristic of a daemon thread?
used for background tasks like garbage collection
It prevents the JVM from shutting down
terminated when all non-daemon threads finish execution
It runs in the background
11
In Java, a subclass can call a constructor of its superclass using:
parent()
super()
base()
this()
12
Which of the following is the correct way to declare a 2D array in Java?
int [] arr []
int arr[] []
int[] [] arr;
All of the above
13
What will be the output of the following code?
cde
bcd
abc
bcde
14
How do you initialize a 2D array with 3 rows and 4 columns?
int [] arr = new int[3] [4];
int [] [] arr = new int[4] [4];
int arr[] [] = new int[4] [3];
int [] [] arr = new int[3] [4];
15
What is the output when a division by zero occurs in a Java program?
None
ArithmeticException
NullPointerException
IOException
16
Consider the following code snippet. What concept is demonstrated?
Method overloading
Encapsulation
Abstraction
Method overriding
17
How many String objects are created in the following code?
3
2
4
1
18
Which of the following is the correct way to create a thread in Java?
Implementing the Runnable interface
None of the above
Both a and b
Extending the Thread class
19
What is the default value of elements in a 2D array of integers in Java?
1
0
undefined
null
20
Which access modifier is commonly used to achieve encapsulation in Java?
private
final
volatile
static
21
If a superclass method is private, can it be overridden by the subclass?
Yes, but only if it is explicitly declared in the subclass.
Yes, but only if the subclass is in the same package.
Yes, it can be overridden regardless of the package.
No, private methods cannot be overridden.
22
Which of the following concepts is essential for achieving run time polymorphism in Java?
All of the above
Abstraction
Encapsulation
inheritance
23
Which exception is thrown when an array is accessed with an illegal index?
NullPointerException
NumberFormatException
ClassCastException
ArrayIndexOutOfBoundsException
24
Which of the following is an example of runtime polymorphism?
Method overloading
Operator overloading
Method overriding
Function overloading
25
What is the output of the following code?
child display
Runtime error
Parent display
Compilation error
26
How do you declare an abstract class in Java?
class ClassName { abstract }
class ClassName abstract {}
abstract class ClassName {}
class abstract ClassName {}
27
Which keyword is used to prevent a class from being inherited in Java?
final
private
static
protected
28
If a class B inherits from class A, which is true?
B and A are independent.
A is a subclass of B.
A is a superclass of B
B is a superclass of A
29
Which of the following is not a type of exception in Java?
Checked Exception
Runtime Exception
Unchecked Exception
Error Exception
30
Which of the following is a checked exception?
ArithmeticException
NullPointerException
ClassNotFoundException
ArrayIndexOutOfBoundsException
31
Which type of polymorphism is achieved by method overloading?
Ad-hoc polymorphism
Runtime polymorphism
Parametric polymorphism
Compile-time polymorphism
32
Can an abstract class in Java implement an interface?
No
Yes
33
What will be the output of the following code?
4
5
3
6
34
Which of the following is not allowed in an abstract class in Java?
Static methods
Final methods
Constructors
Instantiation
35
Which of the following is true about abstract methods in Java?
They do not have a body
They have a body
They must be static
They cannot be overridden
36
What allows a subclass to provide a specific implementation of a method that is already defined by its superclass?
Method Shadowing
Method Hiding
Method Overloading
Method Overriding
37
What will happen if two threads have the same priority?
The execution order will depend on the thread scheduler
The thread that was created first will execute first
Both threads will execute simultaneously
The thread with the higher ID will execute first
38
Which keyword is used to declare an exception that must be handled or propagated in a method signature?
throw
final
catch
throws
39
Which of the following best describes polymorphism in object-oriented programming?
The concept of wrapping data and methods into a single unit.
creating functions with the same name but different implementations.
defining a new class based on an existing class.
The ability of a variable, function, or object to take on multiple forms
40
Which of the following statements about arrays in Java is incorrect?
Arrays in Java are dynamically resizable.
The length of an array is fixed once it is created.
Arrays in Java can hold primitive data types.
Arrays in Java can hold objects.
41
Which of the following statements is true about abstract classes and interfaces in Java?
Interfaces can implement methods; abstract classes cannot
Both can implement methods
Abstract classes can implement methods; interfaces cannot
Neither can implement methods
42
If a try block has multiple catch blocks, how many of them will be executed?
It depends on the exception
None of them
All of them
Only the first one that matches the exception type
43
How can you determine the number of rows in a 2D array arr?
arr[0].length[0]
arr.length
arr[0].length
arr.length[0]
44
What is the significance of the Thread.sleep(0) call?
immediately yield execution to other threads of the same priority
It puts the thread to sleep for a very short amount of time
It does nothing
It makes the thread sleep indefinitely
45
Can an abstract class in Java have a constructor?
no
yes
46
What does the join() method do?
It terminates a thread
It waits for a thread to die
It starts a new thread
It combines two threads
47
What will be the output of the following code?
4
7
5
6
48
Which method would you use to concatenate two strings in Java?
add()
join()
concat()
append()
49
What is the correct syntax to catch multiple exceptions in Java?
catch (Exception1 or Exception2 e)
catch (Exception1 | Exception2 e)
catch (Exception1 & Exception2 e)
catch (Exception1, Exception2 e)
50
What is an abstract class in Java?
A class with only private methods
A class with no methods
A class that can only be instantiated once
A class that cannot be instantiated
51
In which package is the Thread class defined?
java.threading
java.util
java.io
java.lang
52
What is the primary reason for the immutability of Java strings?
To save memory
To enable string pooling
To ensure security
All of the above
53
Which of the following methods is used to compare two strings lexicographically?
lexicograph()
equals()
compare()
compareTo()
54
Which of the following can an abstract class in Java contain?
Only concrete methods
Only abstract methods
Both abstract and concrete methods
Only static methods
55
Which of the following is true about encapsulation?
It binds together the data and functions that manipulate the data
It allows a class to be instantiated multiple times
It allows a class to have more than one superclass
It hides the implementation details from the user
56
Which of the following is true about the try block?
It must be followed by either a catch or finally block.
It cannot be used without a catch block.
It can be followed by a finally block only.
It must be followed by a catch block
57
Which keyword is used to manually throw an exception in Java?
throw
thrown
Throwable
throws
58
What is the output of the following code?
error
1020
10 20
30
59
Which of the following statements is true about string literals in Java?
They are stored in the heap memory.
They are objects created using the new keyword
They are mutable
C. They are stored in the string pool
60
Which of the following methods is used to compare two strings in Java and return true or false?
compareTo()
compare()
equals()
compareWith()
61
What is the output of the following code?
1020
hello
hello30
hello1020
62
Which of the following methods converts all characters in a string to uppercase?
upper()
toUpper()
toCaps()
toUpperCase()
63
Which of the following statements is true about polymorphism?
Polymorphism is only applicable to methods, not to operators.
Polymorphism does not support dynamic method binding.
Polymorphism allows for the implementation of inheritance.
it can be achieved through both method overloading and method overriding.
64
In the context of polymorphism, what does the term "late binding" refer to?
Binding the variable to its type at compile time.
Binding the function call to the function definition at runtime.
Binding the variable to its type at runtime.
Binding the function call to the function definition at compile time.
65
What is the result of the following code?
true
false
66
Which of the following is an example of encapsulation?
A function that calls another function
A class that contains methods to manipulate its own data
A class that inherits from another class
A class that contains static methods
67
What will happen if the run() method is called directly instead of using the start() method?
The thread will not run at all
The thread will run as a normal method call in the current thread
An exception will be thrown
The thread will start running in a new thread
68
Can an abstract class in Java have static methods?
Yes
Only if they are final
No
Only if they are private
69
What does the throws keyword indicate?
That the method will never throw an exception.
That an exception is thrown but not handled within the method.
None of the above.
That an exception is caught within the method.
70
What is the default priority of a thread in Java?
5
1
10
0
71
What is the main purpose of using encapsulation in software development?
To increase code execution speed
To reduce memory usage
To hide implementation details and protect object integrity
To facilitate multiple inheritance
72
What does the following code print?
3
2
4
0
73
Given the 2D array initialization:
6
5
9
8
74
Which method is used to check if a thread is alive?
isAlive()
isRunning()
Sleep()
Start()
75
Which of the following is an unchecked exception?
SQLException
ClassNotFoundException
IOException
NullPointerException
76
In Java, which method is used to retrieve the description of an exception?
printStackTrace()
getCause()
getMessage()
toString()
77
Which of the following is the superclass of all exceptions in Java?
RunTimeException
Error
Throwable
Exception
78
What is the main benefit of using polymorphism?
Easier debugging of the program
Enhanced code reusability and flexibility
Improved readability of code
Increased performance of the program
79
What is encapsulation in object-oriented programming?
The ability to use methods from another class
The ability to hide internal data from outside access
The ability to inherit properties from another class
The ability to use a single interface to represent different data types
80
Can an abstract class in Java have a main method?
No
Yes
81
What keyword is used to inherit a class in Java?
extends
implements
inherits
super
82
What is the primary mechanism behind runtime polymorphism in Java?
Dynamic binding
Static binding
Method overloading
Operator overloading
83
Which block of code is executed no matter whether an exception is handled or not?
Finally
try
catch
finally
84
In Java, how can you access a private member of a class from outside the class?
Using a static method
Directly accessing the member
Using a public get or set method
Using a protected method
85
Which of the following is NOT a valid state for a thread in Java?
Stop
new
Waiting
Running
86
Which of the following is not inherited by subclasses in Java?
Public methods
Protected methods
Private methods
Public fields
87
Which keyword is used to define private members in java?
Private
private
static
protected
88
What happens if a class in Java inherits from an abstract class but does not implement all of its abstract methods?
The class becomes an abstract class
The class can still be instantiated
The program will not compile
The class is automatically made final
89
Which keyword is used to call the constructor of the parent class?
super
parent
extends
this
90
What will be the output of the following code?
Java Programming /n Java Programming
Java Programming /n Java
Compilation error
Java /n Java
91
Which method is used to pause the execution of a thread for a specified amount of time?
suspend()
pause()
wait()
sleep()
92
Which type of method is typically used to access or modify the private attributes of a class?
static method
class method
Constructor
getter and setter method
93
What method is used to start the execution of a thread in Java?
run()
begin()
execute()
start()

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