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Java MCQ: What is a LinkedHashSet in Java? a) A set that maintains insertion order b) A set that does not allow duplicates but is unordered c) A list that allows duplicates d) A map that stores key-value pairs Answer: a) A set that maintains insertion order Explanation: A LinkedHashSet in Java is a set […]

Java MCQ: What is a HashSet in Java? a) A collection that does not allow duplicates and is unordered b) A collection that maintains insertion order c) A collection that maps keys to values d) A collection that allows duplicates Answer: a) A collection that does not allow duplicates and is unordered Explanation: A HashSet

Java MCQ: What does the Set interface represent? a) A collection that does not allow duplicates b) A collection that allows null values c) A collection that maintains order d) A collection that maps keys to values Answer: a) A collection that does not allow duplicates Explanation: The Set interface in Java represents a collection

Java MCQ: What is a Vector in Java? a) A synchronized, dynamic array b) A type of linked list c) An unsynchronized array d) A set that does not allow duplicates Answer: a) A synchronized, dynamic array Explanation: A Vector in Java is a synchronized, dynamic array that can grow as needed. It allows elements

Java MCQ: What is a Stack in Java? a) A last-in, first-out (LIFO) data structure b) A first-in, first-out (FIFO) data structure c) A collection that does not allow duplicates d) A collection that maps keys to values Answer: a) A last-in, first-out (LIFO) data structure Explanation: A Stack in Java is a last-in, first-out

Java MCQ: What is the difference between ArrayList and LinkedList? a) ArrayList uses a dynamic array, LinkedList uses a doubly linked list b) ArrayList allows duplicates, LinkedList does not c) ArrayList is thread-safe, LinkedList is not d) ArrayList does not allow null elements, LinkedList does Answer: a) ArrayList uses a dynamic array, LinkedList uses a

Java MCQ: What is the List interface in Java? a) A collection that stores elements in an ordered sequence b) A collection that does not allow duplicates c) A collection that maps keys to values d) A collection that supports random access Answer: a) A collection that stores elements in an ordered sequence Explanation: The

Java MCQ: What does the Collection interface represent in Java? a) A group of objects b) A single object c) A database connection d) A multithreading mechanism Answer: a) A group of objects Explanation: The Collection interface in Java represents a group of objects, known as elements. It is the root interface of the Java

Java MCQ: What is the Java Collections Framework? a) A set of classes and interfaces for storing and manipulating groups of data b) A framework for managing database connections c) A framework for handling files d) A framework for multithreading Answer: a) A set of classes and interfaces for storing and manipulating groups of data

Java MCQ: What is multithreading in Java? a) Executing multiple threads simultaneously b) Executing multiple programs simultaneously c) Executing a single thread sequentially d) Compiling multiple files Answer: a) Executing multiple threads simultaneously Explanation: Multithreading in Java refers to the ability of a program to execute multiple threads concurrently, allowing for parallel processing and more

Java MCQ: What does the ‘synchronized’ keyword do? a) It allows only one thread to access a block of code at a time b) It prevents deadlock c) It synchronizes two variables d) It ensures a method is called in order Answer: a) It allows only one thread to access a block of code at

Java MCQ: What is an enum in Java? a) A special class that represents a group of constants b) A class that wraps a primitive type c) A type of array d) A collection type Answer: a) A special class that represents a group of constants Explanation: An enum in Java is a special class

Java MCQ: What is a wrapper class in Java? a) A class that converts primitive data types into objects b) A class that handles arrays c) A class that wraps other classes d) A class that stores collections Answer: a) A class that converts primitive data types into objects Explanation: A wrapper class in Java

Java MCQ: What is the difference between an interface and an abstract class? a) Interfaces can have default methods, abstract classes cannot b) Interfaces support multiple inheritance, abstract classes do not c) Abstract classes can have constructors, interfaces cannot d) All of the above Answer: d) All of the above Explanation: Interfaces and abstract classes

Java MCQ: What is an interface in Java? a) A blueprint for classes b) A class with methods c) A class without variables d) A final class Answer: a) A blueprint for classes Explanation: An interface in Java is a blueprint for classes, defining methods that the implementing classes must provide. Interfaces allow for multiple

Java MCQ: What is an abstract class in Java? a) A class that cannot be instantiated b) A class with all abstract methods c) A class that can be instantiated d) A class without methods Answer: a) A class that cannot be instantiated Explanation: An abstract class in Java is a class that cannot be

Java MCQ: What does the ‘throw’ keyword do in Java? a) Catches an exception b) Throws an exception manually c) Declares an exception d) Suppresses an exception Answer: b) Throws an exception manually Explanation: The throw keyword in Java is used to manually throw an exception, typically when a specific error condition is met. This

Java MCQ: What does the ‘finally’ block do in Java? a) Executes code after the try-catch block b) Skips exception handling c) Defines a constant d) Terminates the program Answer: a) Executes code after the try-catch block Explanation: The finally block in Java is used to execute code after a try-catch block, regardless of whether

Java MCQ: What is the ‘try-catch’ block used for in Java? a) Handling exceptions b) Looping through arrays c) Declaring variables d) Defining classes Answer: a) Handling exceptions Explanation: The try-catch block in Java is used to handle exceptions that may occur during the execution of a program. The try block contains code that might

Java MCQ: What is encapsulation in Java? a) Hiding the internal state and requiring all interaction to be performed through methods b) Inheriting methods from a superclass c) Overriding methods in a subclass d) Converting one data type to another Answer: a) Hiding the internal state and requiring all interaction to be performed through methods

Java MCQ: What is inheritance in Java? a) A mechanism to create new classes from existing ones b) A way to encapsulate data c) A method of overloading d) A way to convert data types Answer: a) A mechanism to create new classes from existing ones Explanation: Inheritance in Java is a mechanism that allows

Java MCQ: What is method overriding in Java? a) Defining a method with the same name and parameters in a subclass b) Defining a method with a different name c) Defining multiple methods in a class d) Defining a method with the same name but different parameters Answer: a) Defining a method with the same

Java MCQ: Which of the following is true about method overloading? a) Methods with the same name and parameters b) Methods with the same name but different parameters c) Methods with different names d) Methods with the same return type Answer: b) Methods with the same name but different parameters Explanation: Method overloading in Java

Java MCQ: What is a Java string? a) A primitive data type b) An object that represents a sequence of characters c) A collection of integers d) A type of array Answer: b) An object that represents a sequence of characters Explanation: In Java, a string is an object that represents a sequence of characters.

Java MCQ: What is an array in Java? a) A collection of elements of different types b) A collection of elements of the same type c) A single object d) A variable Answer: b) A collection of elements of the same type Explanation: An array in Java is a collection of elements of the same