Object-oriented programming (OOP) is a fundamental programming paradigm in Java. Key concepts include classes, objects, inheritance, polymorphism, encapsulation, and abstraction. Mastering these concepts is essential for any Java developer.
To explore OOP concepts in detail, visit our article: Object-Oriented Programming Concepts.
A class is a blueprint for creating objects in OOP.
An object is an instance of a class.
Inheritance is a mechanism where a new class inherits properties and behavior from an existing class.
Polymorphism allows methods to do different things based on the object it is acting upon.
Encapsulation is the bundling of data and methods that operate on that data within one unit, typically a class.
Abstraction is the concept of hiding the complex reality while exposing only the necessary parts.
A constructor is a special method used to initialize objects.
Method overloading allows multiple methods to have the same name with different parameters.
Method overriding allows a subclass to provide a specific implementation of a method that is already defined in its superclass.
An interface is a reference type in Java, similar to a class, that can contain only constants, method signatures, default methods, static methods, and nested types.
An abstract class cannot be instantiated and can contain abstract methods that must be implemented by subclasses.
An interface can only contain method signatures and final variables, while an abstract class can have method implementations and instance variables.
A package is a namespace that organizes a set of related classes and interfaces.
The 'this' keyword refers to the current object in a method or constructor.
The 'super' keyword is used to refer to the immediate parent class object.
A static method belongs to the class rather than any specific instance and can be called without creating an object.
A final class cannot be subclassed.
A final method cannot be overridden by subclasses.
A final variable cannot be reassigned once it has been initialized.
Constructor overloading allows a class to have more than one constructor with different parameters.
A nested class is a class defined within another class.
A local class is defined within a method and can only be accessed within that method.
An anonymous class is a class without a name that is declared and instantiated in a single statement.
== checks for reference equality, while .equals() checks for value equality.
A Java Bean is a reusable software component that follows certain conventions, including having a no-argument constructor and providing getter and setter methods.
The Java Collections Framework is a set of classes and interfaces that implement commonly reusable collection data structures.
A List is an ordered collection that can contain duplicate elements.
A Set is a collection that cannot contain duplicate elements.
A Map is an object that maps keys to values, where each key is unique.
ArrayList is backed by an array and provides fast random access, while LinkedList is backed by a doubly linked list and provides faster insertions and deletions.
A HashMap is a Map that uses a hash table for storage, allowing for fast retrieval based on keys.
A TreeMap is a Map that is sorted according to the natural ordering of its keys or by a comparator provided at map creation time.
A Stack is a collection that follows the Last In First Out (LIFO) principle.
A Queue is a collection that follows the First In First Out (FIFO) principle.
A thread is a lightweight process that can run concurrently with other threads.
Synchronization is the process of controlling access to shared resources by multiple threads.
A deadlock is a situation where two or more threads are blocked forever, waiting for each other.
Exception handling is a mechanism to handle runtime errors, allowing the program to continue its execution.
A try-catch block is used to catch exceptions that may occur in the try block and handle them in the catch block.
A finally block is used to execute code after a try-catch block, regardless of whether an exception was thrown or not.
A checked exception is an exception that must be either caught or declared in the method signature.
An unchecked exception is an exception that does not need to be declared or caught.
A lambda expression is a concise way to represent an anonymous function that can be passed around as a parameter.
A stream is a sequence of elements that can be processed in a functional style.
A collection is a data structure that stores elements, while a stream is a sequence of elements that can be processed.
The JVM is an abstract computing machine that enables a computer to run Java programs.
The JRE is a package that provides the libraries, Java Virtual Machine (JVM), and other components to run Java applications.
The JDK is a software development kit that provides tools for developing Java applications, including the JRE.
Garbage collection is the process of automatically freeing memory by deleting objects that are no longer in use.
String is immutable, while StringBuilder and StringBuffer are mutable. StringBuffer is synchronized, making it thread-safe, while StringBuilder is not.