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Java Basics
1/25
What is the purpose of the 'finalize' method in Java?
To initialize variables
To clean up resources before an object is garbage collected
To finalize a class definition
To finalize variable assignments
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2/25
What is the primary purpose of the 'super' keyword in Java?
To call a method of the parent class
To declare variables
To create a new instance of the parent class
To override a method in the child class
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3/25
What is the default value of a static variable in Java?
0 or null, depending on the type
1
undefined
It does not have a default value
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4/25
What is the return type of the hashCode() method in Java?
Object
long
int
String
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5/25
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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6/25
In Java, which of the following is a valid way to declare an array?
int array[5];
int[] array = new int[5];
array = new int[5];
int array[] = new int[5];
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7/25
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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8/25
In Java, what is the difference between '==' and 'equals()'?
'==' checks for value equality, 'equals()' checks for reference equality
'==' checks for reference equality, 'equals()' checks for value equality
There is no difference
'equals()' is used only for strings
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9/25
What does the '@Override' annotation do in Java?
Indicates that a method is being replaced from the parent class
Marks a method that cannot be overridden
Overrides the default values of variables
Signals the use of overridden methods from an interface
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10/25
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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11/25
What does the 'abstract' keyword signify in a Java class?
The class can't be instantiated directly
The class is fully implemented
The class is optimized for performance
The class can be instantiated multiple times
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12/25
Which method must be implemented in a class that implements the java.util.Comparator interface?
compare()
compareTo()
equals()
hashCode()
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13/25
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
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14/25
In Java, what is the purpose of the Collections.sort() method?
To sort elements of a collection in descending order
To randomly shuffle elements of a collection
To sort elements of a collection in ascending order
To reverse the order of elements in a collection
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15/25
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
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16/25
What is the purpose of the 'instanceof' operator in Java?
To compare the performance of two objects
To determine if a specific object is an instance of a class, superclass, or interface
To instantiate a new object of a class
To check the equality of two objects
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17/25
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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18/25
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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19/25
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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20/25
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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21/25
In Java, what is the default layout manager for the JFrame container?
FlowLayout
GridLayout
BorderLayout
CardLayout
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22/25
What is 'JDBC' in Java?
Java Database Connectivity, a standard API for database access
Java Data Binding Code, a framework for binding data to UI elements
Just-in-time Database Compiler, a tool for database optimization
Java Deployment and Compilation, a deployment tool
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23/25
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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24/25
What is 'polymorphism' in the context of Java?
The ability of a variable to hold objects of different types
The ability of Java to run on different platforms without modification
The ability of a method to perform different tasks based on the object
Changing the behavior of an object at runtime
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25/25
In Java, which method would you use to compare two String objects for content equality?
compareTo()
equals()
match()
equalContent()
Next >
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