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Showing posts with the label Java Basics

Variables, Data Types, and Operators in Java

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Chapter 4: Variables, Data Types, and Operators in Java Chapter 4: Variables, Data Types, and Operators in Java In this chapter, we’ll dive into the foundational elements of Java: variables , data types , and operators . Understanding these concepts is essential to start writing functional Java programs. 1. Java Variables Variables are containers for storing data values. In Java, you must declare a variable before you use it. int age = 25; String name = "John"; Here, int and String are data types, while age and name are variable names. Types of Variables Local Variable – Declared inside a method. Instance Variable – Declared inside a class but outside any method. Static Variable – Declared with the static keyword. 2. Java Data Types Java is a statically typed language, meaning all variables must be declared with a data type. Primitive Data Types byte – 1 byte, range: -128 to 127 ...

Arrays and Strings in Java

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Chapter 6: Arrays and Strings in Java Chapter 6: Arrays and Strings in Java Welcome to Chapter 6 of our Java Programming Course! In this chapter, we'll explore two of the most fundamental data structures in Java: Arrays and Strings . 🔹 What is an Array in Java? An Array is a collection of elements, all of the same type, stored in contiguous memory locations. It allows you to store multiple values in a single variable. 👉 Declaration and Initialization int[] numbers = new int[5]; // Declaration numbers[0] = 10; numbers[1] = 20; // ... up to index 4 👉 Shortcut Initialization int[] numbers = {10, 20, 30, 40, 50}; 👉 Accessing Array Elements System.out.println(numbers[2]); // Output: 30 👉 Array Length System.out.println("Length: " + numbers.length); 🔹 Multidimensional Arrays int[][] matrix = { {1, 2, 3}, {4, 5, 6} }; 🔹 Looping Through Arrays for (int i = 0; i < numbers.length; i++) { System.out.println(numbers[i]); ...

Introduction to Java

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Chapter 1: Introduction to Java 1.1 What is Java? Java is a high-level, object-oriented, platform-independent programming language developed by Sun Microsystems (now owned by Oracle). It is used to build web, mobile, desktop, and enterprise applications. It follows the WORA principle — Write Once, Run Anywhere — allowing compiled code to run on any device with the JVM (Java Virtual Machine). 1.2 History of Java Java was created by James Gosling and his team at Sun Microsystems in 1995. Originally named Oak, it was designed for interactive television, but later rebranded as Java and optimized for web applications. 1.3 Features of Java Simple: Easy to learn and use, especially for those familiar with C/C++. Object-Oriented: Promotes modularity, code reuse, and better structure. Platform-Independent: Runs on any OS with JVM. Secure: Uses sandboxing and classloaders to prevent malicious code. Robust: Strong memory management, garbage collect...

Java Syntax and Basic Structure

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  Chapter 3: Java Syntax and Basic Structure 3.1 Structure of a Java Program A basic Java program follows a specific structure that includes: Class definition main() method (entry point) Statements inside curly braces Example: Public class MyProgram { public static void main(String[] args) { System.out.println("Java is powerful!"); } } 3.2 Components of a Java Program 3.3 Java Syntax Rules Java is case-sensitive: Main ≠ main File name must match the class name (for public class) The main() method must be exactly: public static void main(String[] args) 3.4 Java Comments Comments are used to make code easier to understand. Single-line comment: // This is a single-line comment Multi-line comment: /* This is a multi-line comment */ Documentation comment (for APIs): /** * This class prints Hello World. */ 3.5 Printing Output in Java We use System.out.println() or System.out.print() to show output. ➤ Example: System.out.println("Welcome!"); System.out.print("Hello ...