What is Java?

Java is a high-level, general-purpose, object-oriented, and secure programming language developed by James Gosling at Sun Microsystems, Inc. in 1991. It is formally known as OAK. In 1995, Sun Microsystem changed the name to Java. In 2009, Sun Microsystem takeover by Oracle Corporation.

Because of its platform neutrality, Java is a popular object-oriented programming language that enables programmers to create code that can run on any device that has a Java Virtual Machine (JVM). Strong typing, automatic memory management (garbage collection), a large library of standard libraries, and other features make it a popular choice for developing online services, Android mobile apps, enterprise-level applications, and more. Its broad popularity across multiple industries can be attributed to its strong security features, which include a sandbox environment.

Editions of Java

Each edition of Java has different capabilities.

1. Java Standard Editions (JSE): It is used to create programs for a desktop computer.
2. Java Enterprise Edition (JEE): It is used to create large programs that run on the server and manages heavy traffic and complex transactions.
3. Java Micro Edition (JME): It is used to develop applications for small devices such as set-top boxes, phone, and appliances.
4. Java Card: It is a specialized edition of Java designed for smart cards and other small-memory devices, enabling secure elements in devices like SIM cards and credit cards.
5. JavaFX: While not an edition of Java per se, JavaFX is a platform for creating rich internet applications (RIAs) and is often considered alongside Java SE for desktop and web application development. It provides tools for building user interfaces and multimedia content.

Types of Java Applications

There are four types of Java applications that can be created using Java programming:

• Standalone Applications: Java standalone applications uses GUI components such as AWT, Swing, and JavaFX. These components contain buttons, list, menu, scroll panel, etc. It is also known as desktop alienations.
  These programmes might be as basic as utilities or as sophisticated as productivity aids. Platform-independent standalone Java applications are compiled into executable files that can run on any computer that has the Java Virtual Machine (JVM) installed.
• Enterprise Applications: An application that is distributed in nature is called an enterprise application. Enterprise applications frequently incorporate technologies such as Java Message Service (JMS), Java Persistence API (JPA), Java Message Service (EJB), and JavaServer Faces (JSF).
  Java EE offers a range of APIs and specifications for building scalable, secure, and transactional systems, including web services, messaging systems, and enterprise integration solutions.
• Web Applications: An applications that run on the server is called web applications. We use JSP, Servlet, Spring, and Hibernate technologies for creating web applications.
  Technologies like Servlets, JavaServer Pages (JSP), JavaServer Faces (JSF), Spring Framework, and Hibernate are commonly used in the development of Java online applications. Simple websites to intricate online portals, e-commerce platforms, content management systems (CMS), and enterprise resource planning (ERP) systems are some examples of these applications. Java web applications follow the guidelines of server-side programming, in which requests from clients are processed by the server, which then creates dynamic content and replies to the clients.
• Mobile Applications: Java ME is a cross-platform to develop mobile applications which run across smartphones. Java is a platform for App Development in Android.
  Furthermore, the main programming language used for Android app creation is Java, which gives programmers the ability to construct a vast array of mobile applications for the Android operating system.

Java Platform

Java Platform is a collection of programs. It helps to develop and run a program written in the Java programming language. Java Platform includes an execution engine, a compiler and set of libraries. Java is a platform-independent language.

1. Java Virtual Machine (JVM): The JVM is a crucial component of the Java Platform, responsible for executing Java bytecode. It abstracts the underlying hardware and operating system, providing a consistent runtime environment for Java applications. JVM implementations are available for different platforms, allowing Java programs to run on diverse systems without modification.
2. Java Development Kit (JDK): The JDK is a software development kit that includes the necessary tools for developing Java applications. It consists of the Java compiler (javac), the Java runtime environment (JRE), and various development tools such as the debugger, profiler, and documentation generator. The JDK also includes the Java API (Application Programming Interface) documentation, which provides detailed information about the classes and methods available in the Java standard libraries.
3. Java Standard Libraries: Java Platform provides a rich set of standard libraries known as the Java Standard Edition (Java SE) API. These libraries offer a wide range of functionality for tasks such as input/output operations, networking, data manipulation, concurrency, and graphical user interface (GUI) development. By leveraging these libraries, developers can build robust and feature-rich Java applications with minimal effort.

Features of Java

1. Simple: Java is a simple language because its syntax is simple, clean, and easy to understand. Complex and ambiguous concepts of C++ are either eliminated or re-implemented in Java. For example, pointer and operator overloading are not used in Java.
2. Object-Oriented: In Java, everything is in the form of the object. It means it has some data and behavior. A program must have at least one class and object.
3. Robust: Java makes an effort to check error at run time and compile time. It uses a strong memory management system called garbage collector. Exception handling and garbage collection features make it strong.
4. Secure: Java is a secure programming language because it has no explicit pointer and programs runs in the virtual machine. Java contains a security manager that defines the access of Java classes.
5. Platform-Independent: Java provides a guarantee that code writes once and run anywhere. This byte code is platform-independent and can be run on any machine.
   
6. Portable: Java Byte code can be carried to any platform. No implementation-dependent features. Everything related to storage is predefined, for example, the size of primitive data types.
7. High Performance: While Java is often associated with being an interpreted language, modern JVM implementations include sophisticated optimization techniques that can rival the performance of natively compiled languages. Just-In-Time (JIT) compilation, adaptive optimization, and other runtime optimizations contribute to the high performance of Java applications.
8. Distributed: Java also has networking facilities. It is designed for the distributed environment of the internet because it supports TCP/IP protocol. It can run over the internet. EJB and RMI are used to create a distributed system.
9. Multi-threaded: Java also supports multi-threading. It means handling more than one job at a time. Multithreading is essential for building responsive and scalable applications, such as web servers, where multiple clients need to be serviced concurrently.
10. Dynamic: Java supports dynamic loading of classes and dynamic memory allocation, enabling features such as reflection and runtime type information. Reflection allows programs to examine or modify their own structure and behavior at runtime, facilitating advanced meta-programming techniques.
11. Scalable: Java's scalable architecture makes it suitable for developing applications ranging from small utilities to large-scale enterprise systems. Its modular design encourages code organization and reusability, making it easier to manage and maintain complex projects over time.

OOPs (Object Oriented Programming System)

Object-oriented programming is a way of solving a complex problem by breaking them into a small sub-problem. An object is a real-world entity. It is easier to develop a program by using an object. In OOPs, we create programs using classes and object in a structured manner.

1. Class: A class is a template, blueprint, or prototype that defines the data members and methods of an object. An object is the class's instance. We can define a class by using the class keyword.
2. Object: An object is a real-world entity that can be identified distinctly. For example, a desk or a circle can be considered an object. An object has a unique behavior, identity, and state. Data fields with their current values represent the state of an object (also known as its properties or attributes).
3. Abstraction: An abstraction is a method of hiding irrelevant information from the user. For example, the driver only knows how to drive a car; there is no need to know how the car runs. We can make a class abstract by using the keyword abstract. In Java, we use abstract classes and interfaces to achieve abstraction.
4. Encapsulation: An encapsulation is the process of binding data and functions into a single unit. A class is an example of encapsulation. In Java, Java bean is a fully encapsulated class.
5. Inheritance: Inheritance is the mechanism in which one class acquires all the features of another class. We can achieve inheritance by using the extends keyword. It facilitates the reusability of the code.
6. Polymorphism: The polymorphism is the ability to appear in many forms. In other words, single action in different ways. For example, a boy in the classroom behaves like a student, and in the house behaves like a son. There are two types of polymorphism: run-time polymorphism and compile-time polymorphism.
7. Method Overriding: A feature of inheritance known as "method overriding" allows a subclass to provide a unique implementation of a method that is already defined in the superclass. When a subclass overrides a method, it substitutes its own implementation for the one inherited from the superclass. Through method overriding, subclasses can alter or expand the functionality of inherited methods, enabling runtime polymorphism.
8. Method Overloading: Java's feature known as "method overloading" enables a class to have numerous methods with the same name but distinct argument lists. Developers can provide multiple ways to execute a method based on different combinations of arguments by allowing overload methods to have varied numbers or types of parameters. Code readability, flexibility, and reusability are all improved by method overloading.