Java Programming Fundamentals and Core Features
Introduction to Java and Its Key Features
Java is a high-level, object-oriented programming language developed by Sun Microsystems in 1995 (now owned by Oracle Corporation). It is designed to be simple, secure, portable, and platform-independent.
The main idea behind Java is “Write Once, Run Anywhere (WORA)”, meaning a Java program can run on any device that has a Java Virtual Machine (JVM). Java is widely used for:
- Web applications
- Mobile applications (especially Android)
- Desktop software
- Enterprise
Java Programming Fundamentals and Core Concepts
| Feature | Description |
|---|---|
| OOP | Object-Oriented Programming |
| Java | Core Language |
Java Arrays of Objects
The following example demonstrates how to create an array of objects using a Groceries class to manage item data.
public class Groceries {
int itemId;
String itemName;
double price;
void display() {
System.out.println("Item ID: " + itemId + ", Item Name: " + itemName + ", Price: " + price);
}
public static void main(String[] args) {
// Array of objects
Groceries[Core Java Code Snippets and Programming Fundamentals
1. Control Statements in Java
public class ControlStatementsDemo {
public static void main(String[] args) {
int number = 5;
if (number > 0) {
System.out.println("Number is positive");
} else if (number < 0) {
System.out.println("Number is negative");
} else {
System.out.println("Number is zero");
}
int day = 3;
switch (day) {
case 1: System.out.println("Monday"); break;
case Essential Java Programming Examples and Concepts
Java Programming Examples
1. Reverse Number and Sum of Digits
import java.util.Scanner;
class SumReverse {
int n, rev = 0, sum = 0, r;
Scanner sc = new Scanner(System.in);
void input() {
System.out.print("Enter a Number: ");
n = sc.nextInt();
}
void reverse() {
while (n > 0) {
r = n % 10;
rev = rev * 10 + r;
sum = sum + r;
n = n / 10;
}
System.out.println("Sum of digits: " + sum);
Essential C++ Concepts: Constructors, Inheritance, and Loops
Constructors in C++
Definition: A constructor is a special member function of a class that is automatically called when an object of the class is created. It is mainly used to initialize the data members of the class. The constructor has the same name as the class and it does not have any return type.
Characteristics
- Constructor name is the same as the class name.
- It has no return type (not even void).
- It is automatically executed when the object is created.
- It initializes the data members of the class.
Java Polymorphism, Overloading, Lambdas & Exceptions
Constructor and Method Overloading
class Calculator {
// Constructor overloading: same name, different parameters
Calculator() { System.out.println("Default Calculator created"); }
Calculator(String mode) { System.out.println(mode + " Calculator created"); }
// Method overloading: same name, different parameters
int add(int a, int b) { return a + b; }
double add(double a, double b) { return a + b; }
}
public class OverloadingDemo {
public static void main(String[] args)