![OUR FIRST PROGRAM – HELLO
WORLD
• public class HelloWorld {
• public static void main(String[] args) {
• System.out.println("Hello, World!");
• }
• }
3/1/2024
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![EXPLANATION:
• public class HelloWorld { ... }: This defines a class named HelloWorld. This is the basic
structure for a Java program.
• public static void main(String[] args) { ... }: This is the main method, which is the entry point
for your program execution.
• System.out.println("Hello, World!");: This line prints the string "Hello, World!" to the console.
• System.out: This is a predefined class that provides access to various system
functionalities.
• out: This is a static field of the System class that represents the standard output stream
(typically the console).
• println: This method of the PrintStream class (accessible through System.out) prints the
provided string followed by a newline character.
• This simple program demonstrates the basic building blocks of a Java program: classes,
methods, and printing to the console.
3/1/2024
Package course 01 9](https://image.slidesharecdn.com/demolecture01notes-240301080605-c789a456/85/Demo-Lecture-01-Notes-paid-course-notes-9-320.jpg)
Demo Lecture 01 Notes paid , course notes
- 2. COURSE INSTRUCTOR • Mr Sarthak Gandhi – Founder And CEO Team Sabki Kaksha 3/1/2024 Package course 01 2
- 4. WHY LEARN JAVA ?? • There are several compelling reasons why you might consider learning Java: • High demand and strong job market: Java remains one of the most popular programming languages globally, with millions of developers using it. This translates to a high demand for skilled Java developers in various industries, leading to potentially competitive salaries and ample job opportunities. • Versatility and wide applicability: Java's versatility allows you to build applications for various platforms, including web, mobile, desktop, and enterprise environments. This broadens your career options and makes your skills valuable across different sectors. • Platform independence: One of Java's key strengths is its "write once, run anywhere" (WORA) principle. Code written in Java can run on various operating systems without modification, making it a practical choice for cross-platform development. • Large, supportive community: Java boasts a vast and active community of developers, providing extensive learning resources, tutorials, and forums for support and guidance. This extensive support network can significantly aid your learning journey. • Strong foundation for other languages: Learning Java equips you with a solid understanding of object-oriented programming (OOP) concepts. These fundamental concepts are widely applicable across various programming languages, making it easier to learn other languages in the future. • Abundant libraries and frameworks: Java benefits from a rich ecosystem of libraries and frameworks that simplify development tasks and offer pre-built functionalities. This extensive collection of tools can significantly improve your development efficiency. • Whether you're aiming for a career in software development or simply want to broaden your programming skillset, Java presents a valuable path with its widespread adoption, robust features, and supportive community. 3/1/2024 Package course 01 4
- 5. WHAT IS JAVA? • High-level programming language: Java utilizes a human-readable language that needs to be translated into machine-understandable code for a computer to execute. • Object-oriented programming (OOP): Java focuses on creating objects that contain data (attributes) and behaviors (methods). OOP promotes code reusability, modularity, and easier maintainability of complex projects. • Platform-independent: Java's "write once, run anywhere" capability stems from how it's compiled. Instead of generating direct machine code, a Java compiler turns your code into Java bytecode – an intermediate language. This bytecode can then be executed on any system with a Java Virtual Machine (JVM) installed. 3/1/2024 Package course 01 5
- 6. HOW JAVA WORKS • Writing Java Code: You write Java code in a text editor and save files with the ".java" extension. • Compilation: Using the Java compiler (javac), your ".java" code is converted into platform- independent bytecode (files ending in ".class"). • Execution: The Java Virtual Machine (JVM) loads and interprets the bytecode, translating it into the instructions your specific computer's operating system understands. This is what allows Java to run seamlessly across different platforms. 3/1/2024 Package course 01 6
- 7. KEY FEATURES OF JAVA • Simple and Familiar: Java's syntax is inspired by C and C++, making it relatively easy for programmers familiar with these languages to pick up. • Robust: Java includes features like automatic garbage collection (memory management) and error-handling mechanisms to make programs more reliable and less prone to crashes. • Secure: Java incorporates various security measures at the language level and through runtime environments to protect against malicious code. • Multithreaded: Java supports executing multiple threads of a program concurrently, improving efficiency, especially in resource-intensive applications. 3/1/2024 Package course 01 7
- 8. OUR FIRST PROGRAM – HELLO WORLD • public class HelloWorld { • public static void main(String[] args) { • System.out.println("Hello, World!"); • } • } 3/1/2024 Package course 01 8
- 9. EXPLANATION: • public class HelloWorld { ... }: This defines a class named HelloWorld. This is the basic structure for a Java program. • public static void main(String[] args) { ... }: This is the main method, which is the entry point for your program execution. • System.out.println("Hello, World!");: This line prints the string "Hello, World!" to the console. • System.out: This is a predefined class that provides access to various system functionalities. • out: This is a static field of the System class that represents the standard output stream (typically the console). • println: This method of the PrintStream class (accessible through System.out) prints the provided string followed by a newline character. • This simple program demonstrates the basic building blocks of a Java program: classes, methods, and printing to the console. 3/1/2024 Package course 01 9
- 10. WHY LEARN JAVASCRIPT ?? 3/1/2024 Package course 01 10 Here are some of the compelling reasons to learn JavaScript: 1. Ubiquitous in Web Development: JavaScript is the dominant language for adding interactivity and dynamism to web pages. It's crucial for creating features like: Interactive elements: Forms, drop- down menus, modal windows, and animations. Dynamic content: Updating content without reloading the entire page (e.g., real-time updates). Single-page applications (SPAs): Web applications that feel more like native apps, often relying heavily on JavaScript frameworks. 2. Relatively Beginner-Friendly: Compared to other programming languages, JavaScript has a relatively easy-to-learn syntax, making it a good entry point for beginners. Its interpreted nature allows you to see the results of your code quickly, encouraging experimentation and learning. Abundant learning resources and a large, supportive community exist to guide you through the learning process. 3. Highly Versatile: JavaScript's reach extends beyond web development. It can be used for: Server-side development: Frameworks like Node.js enable building web servers and APIs in JavaScript. Mobile app development: Frameworks like React Native allow creating mobile apps using JavaScript and web technologies. Desktop applications: Tools like Electron enable building desktop applications with JavaScript and web technologies. 4. Strong Job Market: Due to its widespread use, JavaScript developers are in high demand across various industries. Learning JavaScript can open doors to lucrative career opportunities in web development, mobile app development, and other tech fields. 5. Foundation for Learning Other Languages: The fundamentals learned through JavaScript, like object-oriented programming concepts, can be beneficial when learning other programming languages. This provides a strong foundation for exploring other areas of programming. In summary, JavaScript's versatility, strong job market, beginner-friendliness, and value as a learning foundation make it a compelling language to learn in today's tech landscape.
- 11. WHAT IS JAVASCRIPT 3/1/2024 Sample Footer Text 11 JavaScript (often abbreviated as JS) is a high-level, interpreted programming language that has become synonymous with web development. While its primary function is to make web pages interactive and dynamic, it has evolved into a versatile tool applicable in various domains beyond the browser. Here's a breakdown of its key characteristics: 1. Core of Interactive Web Pages: Imagine a static web page as a printed document; JavaScript breathes life into it, allowing for: User interaction: Responding to user actions like clicks, form submissions, or mouse movements. Dynamic content updates: Modifying parts of the page without reloading the entire thing, creating a smoother user experience. Animations and other visual effects: Adding animations and interactive elements to enhance user engagement. 2. Interpreted Language: Unlike compiled languages that require conversion into machine code before execution, JavaScript uses an interpreter. The interpreter reads the code line by line and translates it into instructions the computer understands, making development faster and more flexible. 3. Object-Oriented: JavaScript adheres to object-oriented programming (OOP) principles, where code is organized around objects that encapsulate data (properties) and functionalities (methods). This approach promotes code reusability, modularity, and maintainability. 4. Beyond the Browser: While web development remains its core strength, JavaScript's reach has expanded: Server-side development: Frameworks like Node.js empower developers to build web servers and APIs using JavaScript, enabling real-time communication and data exchange. Mobile app development: Frameworks like React Native allow creating mobile apps using JavaScript and web technologies, offering a single codebase for both web and mobile platforms. Desktop applications: Tools like Electron enable building desktop applications with JavaScript and web technologies, blurring the lines between web and traditional desktop software. 5. Beginner-Friendly: Compared to some other programming languages, JavaScript has a relatively simpler syntax, making it easier to learn, especially for those new to programming. Its interpreted nature allows for quicker experimentation and learning from immediate results. In summary, JavaScript is a powerful and versatile language that has transformed web development and continues to find applications in various domains. Its ease of learning, combined with its vast capabilities, makes it a valuable skill for anyone interested in web development or exploring the broader tech landscape
- 12. HOW JAVASCRIPT WORKS • Browser as the Execution Environment: • When you encounter a web page with JavaScript code, the code is downloaded by your web browser. Unlike compiled languages that run directly on the operating system, JavaScript relies on the browser's JavaScript engine for execution. • 2. The JavaScript Engine: • Each browser has its own JavaScript engine, like Chrome's V8 engine or Firefox's SpiderMonkey. These engines are responsible for: • Parsing: The engine reads the JavaScript code and breaks it down into smaller, understandable pieces, similar to how a grammar analyzer works in natural languages. • Compiling (Just-in-Time, or JIT): Modern engines often use a technique called Just-in- Time (JIT) compilation. Instead of compiling the entire code upfront, the engine translates it into machine code piece by piece as it's being executed. This optimizes performance by focusing on the parts of the code that are actually used. • Executing: The engine interprets the translated code and carries out the instructions, manipulating data and performing actions like modifying the web page content or interacting with the user. • 3. Single-Threaded Execution: • Unlike some other languages, JavaScript is single-threaded, meaning it can only execute one task at a time. This has implications for how asynchronous operations are handled, as we'll see later 3/1/2024 Package course 01 12
- 13. KEY FEATURES - JS • Objects: JavaScript heavily relies on objects to organize code and data. Objects are like blueprints that define properties (data) and methods (functions that operate on that data). This structure promotes code reusability and modularity. • Event-Driven Programming: JavaScript is event-driven, meaning it reacts to events triggered by user interactions (clicks, key presses), browser events (page loading, resizing), or timers. This allows for dynamic and responsive web pages. • Asynchronous Programming: While JavaScript is single-threaded, it can handle asynchronous operations, like fetching data from a server, without blocking the main thread. This is achieved using techniques like callbacks, promises, and async/await, allowing the program to continue executing other tasks while waiting for the asynchronous operation to complete. • Understanding these core principles is crucial for effectively working with JavaScript and creating dynamic and interactive web experiences. 3/1/2024 Package course 01 13
- 14. OUR FIRST PROGRAM- HELLO WORLD console.log("Hello, World!"); 3/1/2024 Package course 01 14
- 16. EXPLANATION : • console: This is a built-in object in JavaScript that provides access to the browser's console, which is typically a window where you can see messages and errors related to your code. • .log(): This is a method of the console object used to print messages to the console. • "Hello, World!": This is the string you want to print, enclosed in double quotes. • How to Run: • There are two main ways to run this code: • In the Browser Console: • Open your web browser's developer tools (usually by pressing F12 or right-clicking and selecting "Inspect"). • Go to the "Console" tab. • Paste the code console.log("Hello, World!"); into the console and press Enter. • You should see "Hello, World!" printed in the console. • In a .html File: • Create a new file and save it with a .html extension (e.g., hello_world.html). • Add the following code inside the <script> tag: 3/1/2024 Package course 01 16