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Java Basics
1/25
What is the purpose of the 'this' keyword in Java?
To refer to the current class instance variable
To create a new instance of a class
To terminate the current method
To invoke a method of the superclass
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2/25
What is the return type of the hashCode() method in Java?
Object
long
int
String
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3/25
What is the effect of marking a method as 'synchronized' in Java?
It makes the method run faster
It allows multiple threads to access the method simultaneously
It ensures only one thread can access the method at a time
It makes the method available to all classes
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4/25
What is the default size of a 'HashSet' in Java?
16
10
12
32
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5/25
Which exception is thrown when trying to access an element with a key that does not exist in a HashMap?
NullPointerException
ArrayIndexOutOfBoundsException
KeyNotFoundException
NoSuchElementException
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6/25
Which of these is an immutable class in Java?
java.lang.StringBuilder
java.lang.String
java.lang.StringBuffer
java.util.ArrayList
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7/25
What is the purpose of the 'package' statement in Java?
To enhance the performance of the application
To create a new thread
To define a namespace for classes
To import external libraries
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8/25
What is 'autoboxing' in Java?
Automatically converting a primitive type into its corresponding wrapper class
The process of optimizing code automatically
Creating an automatic backup of the code
A feature for automatic memory management
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9/25
How do you declare a constant variable in Java?
Using the 'constant' keyword
Using the 'static final' keywords
Using the 'immutable' keyword
Declaring without initialization
Next >
10/25
What is a 'daemon' thread in Java?
A high-priority thread
A thread that runs in the background
A thread that can't be killed
The main thread of an application
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11/25
Which of the following is a checked exception in Java?
NullPointerException
ArrayIndexOutOfBoundsException
IOException
RuntimeException
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12/25
What is the function of the 'native' keyword in Java?
It indicates that the method is implemented in another language like C or C++
It declares a method as part of the native Java library
It optimizes the method for faster execution
It makes the method accessible only within its own package
Next >
13/25
In Java, what is a 'Lambda Expression'?
A concise representation of an anonymous function that can be passed around
A special type of exception
A way to create a new thread
An expression used for array manipulation
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14/25
What is the primary difference between 'StringBuffer' and 'StringBuilder' in Java?
StringBuffer is mutable, while StringBuilder is immutable
StringBuilder is faster as it is not synchronized
StringBuffer can store characters, while StringBuilder cannot
StringBuilder is thread-safe, while StringBuffer is not
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15/25
What is the purpose of the 'volatile' keyword in Java?
To make a variable thread-safe by ensuring atomic access to it
To optimize the code during compilation
To indicate that a variable's value will not change
To store the variable value permanently in the database
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16/25
What is the difference between 'static' and 'non-static' methods in Java?
Static methods can be called without creating an instance of the class
Non-static methods are always synchronized
Static methods are faster
Non-static methods can access any class variable
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17/25
In Java, what is 'reflection' used for?
To modify the behavior of a program at runtime
To duplicate objects
To analyze the performance of applications
To convert primitive types into objects
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18/25
In Java, what is a 'checked' exception?
An exception that is checked at compile-time
An exception that is checked at runtime only
Any exception that occurs during program execution
An exception that cannot be caught or handled
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19/25
In Java, what is the default layout manager for the JFrame container?
FlowLayout
GridLayout
BorderLayout
CardLayout
Next >
20/25
In Java, which keyword is used to inherit properties and methods from a class?
extends
implements
inherits
super
Next >
21/25
How can you achieve thread safety in Java?
By using synchronized blocks or methods
By avoiding the use of multiple threads
By using the 'volatile' keyword
By making all methods and variables private
Next >
22/25
What is the use of the 'implements' keyword in Java?
To inherit from an abstract class
To include an interface in a class
To mark a method as mandatory to override
To declare a class as abstract
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23/25
In Java, which method would you use to compare two String objects for content equality?
compareTo()
equals()
match()
equalContent()
Next >
24/25
What is the advantage of using a 'PreparedStatement' in JDBC?
Faster execution for repeated queries
Allows execution of dynamic queries only
Automatically closes database connections
Improves the UI of the application
Next >
25/25
In Java, what is 'exception chaining'?
Linking multiple exceptions together
Creating a chain of methods that can throw exceptions
Catching multiple exceptions in one catch block
Calling a method that throws an exception from another that also throws an exception
Next >
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