Author: alegru

In Java, a class is a blueprint or a template that defines the properties and behaviours of objects. An object, on the other hand, is an instance of a class, created using the blueprint provided by the class. To illustrate this concept, let’s consider an example of a car. A car can be thought of…

Encapsulation is a fundamental concept in object-oriented programming (OOP) that involves bundling data and behaviour together into a single unit, called a class. The key idea behind encapsulation is to protect the data within a class from being accessed or modified directly by code outside the class. Instead, the class provides methods or functions to…

package vehicle; public class Car { // fields and methods } package vehicle; // OK public class Car { package vehicle; // DOES NOT COMPILE // fields and methods } package vehicle; // DOES NOT COMPILE package vehicle; class Car { public void printRandomNumber() { Random r = new Random(); // DOES NOT COMPILE System.out.println(r.nextInt(10));…

In this tutorial, we will explore the differences between interfaces and abstract classes and when to use each of them. We’ll start with a brief overview of what these two approaches are, and then dive into their characteristics, syntax, and usage in Java. By the end of this tutorial, you will have a solid understanding…

In Java, an interface is a collection of abstract methods that define a contract or a set of behaviors that a class can implement. Interfaces provide a way to achieve abstraction and polymorphism, enabling objects of different classes to be treated interchangeably based on their common behavior. In this tutorial, we will explore the various…

class Vehicle { // … } class Car extends Vehicle { // … } class Test { public static void main(String[] args){ Car car = new Car(); System.out.println(car instanceof Car); System.out.println(car instanceof Vehicle); } } Output: true true   The above example shows that an object of subclass type is also a superclass type. The instanceof operator works…

Java is an object-oriented programming language that allows developers to create reusable and modular code through the use of classes, objects, and interfaces. One of the key features of Java is the concept of binding, which refers to the association of a method call to the corresponding method body. There are two types of binding…

Java is a popular programming language that is used for a wide variety of applications, ranging from web development to mobile app development to machine learning. One of the features of Java that is particularly important for programmers to understand is the “final” keyword. The “final” keyword in Java is used to indicate that a…

In Java, a static initializer block is a block of code that is executed when a class is loaded into memory. It is typically used to perform some initialization tasks that need to be done before the class can be used, such as initializing static variables, registering JDBC drivers, or building complex data structures. In…

public static void main(String[] args) { { System.out.println(“Summer”); } } { System.out.println(“Winter”); } 1 public class Car { 2 private String model = “Ford”; 3 4 { 5 System.out.println(“Instance Initializer block…”); 6 } 7 8 public Car () { 9 model = “Opel”; 10 System.out.println(“Constructor…”); 11 } 12 13 public static void main(String[] args) {…

class Vehicle { void startEngine() { System.out.println(“Starting the engine…”); } void stopEngine() { System.out.println(“Stopping the engine…”); } } class Car extends Vehicle { void move() { System.out.println(“The car is moving…”); } void invoke() { super.startEngine(); move(); super.stopEngine(); } } class TestSuper2 { public static void main(String args[]){ Car car = new Car(); car.invoke(); } }…