In Java, a class can inherit fields and methods from another class using the extends keyword, establishing an IS-A relationship.
Missing Word
extends
The extends keyword is used to declare that a class is a subclass of another class, thereby inheriting its members.
Question 2
The ability of an object to take on many forms, such as an instance of its own class or an instance of a superclass, is known as polymorphism.
Missing Word
polymorphism
Polymorphism allows objects to be treated as instances of their superclass type, enabling flexible and extensible code.
Question 3
By declaring fields as private and providing public methods to access and modify them, Java promotes the principle of encapsulation.
Missing Word
private
The private access modifier restricts direct access to fields from outside the class, supporting encapsulation.
Question 4
An interface in Java defines a contract of methods that a class must implement, providing a form of abstraction.
Missing Word
interface
Interfaces define a set of abstract methods that implementing classes must provide, enforcing a contract without specifying implementation details.
Question 5
An ArrayList is a resizable array implementation of the List interface that allows for dynamic sizing and efficient random access.
Missing Word
ArrayList
ArrayList provides a dynamic array implementation of the List interface, suitable for scenarios requiring frequent element access by index.
Question 6
A HashSet stores unique elements and does not maintain any specific order, leveraging a hash table for performance.
Missing Word
HashSet
HashSet is an implementation of the Set interface that uses a hash table to store only unique elements without preserving insertion order.
Question 7
A HashMap stores key-value pairs where each key is unique, providing efficient retrieval of values based on their associated keys.
Missing Word
HashMap
HashMap is an implementation of the Map interface that stores data in key-value pairs, ensuring unique keys for fast lookups.
Question 8
An IOException is a checked exception, meaning it must be caught or declared in the method signature using a throws clause.
Missing Word
checked
Checked exceptions are those that the Java compiler forces you to handle explicitly, either with a try-catch block or a throws declaration.
Question 9
The catch block is executed if an exception occurs within the corresponding try block.
Missing Word
catch
The catch block specifies the type of exception it can handle and contains the code to execute when such an exception is thrown.
Question 10
Programmers can explicitly signal an exceptional condition by using the throw keyword to create and propagate an exception object.
Missing Word
throw
The throw keyword is used to manually instantiate and propagate an exception object within a program.
Question 11
Generics provide type safety at compile time, reducing the likelihood of ClassCastException at runtime.
Missing Word
safety
Generics enforce type checks during compilation, preventing incompatible types from being assigned and thus improving type safety.
Question 12
The T in public class Box<T> represents a type parameter that will be replaced by a concrete type when the class is instantiated.
Missing Word
parameter
A type parameter acts as a placeholder for a specific type that will be provided when a generic class or method is used.
Question 13
The wildcard ? extends Number allows a generic collection to hold any type that is a subclass of Number, including Number itself.
Missing Word
extends
The ? extends keyword specifies an upper-bounded wildcard, meaning the type can be the specified class or any of its subclasses.
Question 14
Implementing the Runnable interface is a common way to define a task that can be executed by a Java thread.
Missing Word
Runnable
The Runnable interface defines a single run() method, which encapsulates the code to be executed by a thread.
Question 15
The synchronized keyword can be used to protect critical sections of code, ensuring that only one thread can execute them at a time.
Missing Word
synchronized
The synchronized keyword provides a mechanism for controlling access to shared resources, preventing race conditions by allowing only one thread to execute a block of code at a time.
Question 16
A class is considered thread-safe if it behaves correctly when accessed concurrently by multiple threads without needing external synchronization.
Missing Word
thread-safe
Thread safety ensures that concurrent access to an object or data structure does not lead to inconsistent states or unexpected behavior.
Question 17
A deadlock occurs when two or more threads are blocked indefinitely, each waiting for the other to release a resource.
Missing Word
deadlock
Deadlock is a specific condition in concurrent programming where two or more threads are perpetually waiting for each other to release resources, resulting in a standstill.
Question 18
The ExecutorService interface provides a higher-level abstraction for managing and controlling the execution of asynchronous tasks.
Missing Word
ExecutorService
ExecutorService simplifies the management of thread pools and the execution of tasks, abstracting away the direct handling of threads.
Question 19
A constructor is a special method used to initialize new objects, invoked automatically when an object is created using the new keyword.
Missing Word
constructor
Constructors are responsible for initializing the state of an object when it is instantiated.
Question 20
The volatile keyword ensures that changes to a variable are always written to and read from main memory, preventing thread caching issues.
Missing Word
volatile
The volatile keyword guarantees visibility of changes to variables across threads by preventing local caching and forcing reads/writes to main memory.