Java Tutorial



Java Tutorial

Introduction to Java


Among the most popular and versatile programming languages, Java is fantastic for constructing a wide range of applications due to its simplicity, object-oriented approach, and enormous ecosystem. 

This tutorial is intended for prospective programmers at the basic level who are interested in web development, mobile app development, or corporate solutions. It serves as a complete guide, covering the basics of Java, introduction to Java programming, features of Java, and practical applications.

What is Java Programming?

Java has established itself as a pillar in the field of software development. It is renowned for its object-oriented procedure, platform independence, and flexibility. Java allows programmers to develop a single piece of code that can be executed on any machine with a Java Virtual Machine (JVM) setup. 

The object-oriented structure of Java, wherein code is arranged into objects that contain properties (attributes) and behaviors (methods), is one of the language's distinguishing characteristics.

Introduction to Java programming offers numerous advantages for creating and managing large software systems, and this encourages code modularity and scalability. Java offers many built-in classes and APIs for many tasks through its vast standard library. 

Java finds applications across different fields, such as corporate systems, online development, mobile app development (especially for Android), and desktop applications. Like C++ and C#, Java has a syntax similar to the C programming family.

Why is the Java Programming Language Called ‘Java’?

In honor of the coffee beans from Java, Indonesia, the product's designers chose "Java.” It was designed to inspire feelings of vitality and invention, which are consistent with the objectives of the language. Sun Microsystems also registered the name "Java" as a trademark.

Why Use Java?

There are many factors why Java is so widely used in the industry:

  • Object-Oriented Programming: Create reusable objects from code to enable modular and maintainable development.

  • Platform Independence: A Java Virtual Machine (JVM) enables you to write code once and run it across any platform.

  • Large Standard Library: Save time and effort by using various pre-built components for typical activities.

  • Scalability: Scalable application development is made possible by the design and libraries of Java.

  • Security: Application security is improved by features like bytecode verification and a built-in security manager.

  • Robustness and Reliability: Application stability is improved through strong type checking, handling of exceptions, and automated memory management.

  • Community and Ecosystem: Use the vast, encouraging community's wealth of materials and structures.

  • Job Opportunities: Java developers are in great demand due to the extensive use of the language, which offers opportunities for professional advancement.

Features Of Java

The key features of Java include:

  • Object-Oriented Programming (OOP): 

As a completely object-oriented language, Java enables programmers to group code into reusable objects with attributes and behaviors.

  • Platform Independence: 

Java programs may run on any platform because of the JVM (Java Virtual Machine), which bridges the code and the underlying operating system.

  • Garbage Collection: 

Java contains built-in garbage collection that handles memory deallocation and automated memory management.

  • Strong Type Checking: 

Java implements secure type checking to ensure type safety and minimize runtime errors.

  • Exception Handling:

Java has a powerful exception-handling system to detect and manage faults when running programs.

  • Multi-threading:

Java has multithreading capability, allowing concurrent programming and effective system resource management.

  • Rich Standard Library: 

The extensive standard library (API) included with Java offers pre-built classes and methods for various activities, including networking, file management, and user interface creation.

  • Security:

Java emphasizes security and includes tools like bytecode verification, a built-in security manager, and sandboxing to guard against unauthorized operations and guarantee secure execution.

Java Terminology

Here are the essential Java concepts and terminology:

  • Class: A class can be defined as a template or blueprint that defines the properties (data fields) and behaviors (methods) of objects. Classes serve as blueprints for creating multiple instances (objects) of the same type.

  • Object: An object is an instance of a class. It represents a real-world entity or concept and encapsulates data (properties) and behavior (methods).

  • Method: A method is a block of code that performs a specific task. It is defined within a class and can be called (invoked) to execute its functionality. Methods may have parameters (input) and may return a value.

  • Inheritance: Inheritance is a mechanism in Java that allows a class (subclass) to inherit the properties and behaviors of another class (superclass). It enables code reuse and supports the concept of a hierarchical relationship between classes.

  • Interface: An interface is a collection of abstract methods. It defines a contract that classes can implement, specifying the methods they must provide. Interfaces allow for multiple inheritances in Java.

  • Package: A package is a way to organize related classes and interfaces. It provides a namespace to avoid naming conflicts. Packages help in modularizing and organizing code.

  • Exception: An exception is an event that occurs during the execution of a program, resulting in the disruption of the normal flow. Java provides a robust exception-handling mechanism to catch and handle such exceptions, preventing program crashes.

  • Static: The static keyword is used to declare a member (variable or method) that belongs to the class rather than the class's instances (objects). Static members are shared among all instances of the class.

Let us understand some of these concepts with the example below:

Let us now break down the code and understand each part of the program better.

i) Class Declaration

The program begins with declaring a class named upGradTutorials using the class keyword. In Java, every program consists of at least one class. The class is a blueprint that encapsulates the program's code and data.

ii) Main Method

Within the class, we define a main method. The main method is the entry point of the Java program and is executed when the program is run. It has the following syntax: public static void main(String[] args). The main method receives command-line arguments as an array of strings (args), although we do not use them in this program.

iii) Variable Declaration and Initialization

Inside the main method, we declare and initialize two variables, length, and width of type double. These variables represent the dimensions of the rectangle. In this example, we assign the values 5.5 and 3.2 to length and width, respectively.

iv) Calculation of Area

The program calculates the area of the rectangle by multiplying length with width and then stores the result in the variable area of type double. In this case, the calculation is performed using the * operator.

v) Print Result

We use the System.out.println() statement to display the calculated area. This statement is used to print a message or value to the console. In this program, we concatenate the message "The area of the rectangle is: " with the area variable using the + operator.

vi) Parameter of the main Method

The main method takes a single parameter of type String[] named args. This parameter allows command-line arguments to be passed to the program when executed. In this example, we are not utilizing the args parameter, so it remains unused.

Java Development Kit (JDK)

Oracle offers the Java Development Kit (JDK), a software development kit comprising the tools and libraries required for creating Java applications. Along with several other utilities and development tools, it comes with the Java compiler (javac), which converts Java source code into bytecode. The JDK's documentation, reference code, and debugging tools assist developers immensely.

Java Run-time Environment (JRE)

The Java Runtime Environment (JRE) is a software package that offers the required runtime support for running Java applications. It contains the Java Virtual Machine (JVM) and essential class libraries to run Java programs. The JDK's utilities and development tools are not included in the JRE. It is commonly installed on end-user computers to execute Java applications.

Java Virtual Machine (JVM)

A key element of the Java platform is the Java Virtual Machine (JVM). Its duties include deciphering and running Java bytecode. The JVM creates an abstraction layer between Java programs and the underlying hardware and operating system to provide platform independence. By dynamically converting bytecode into machine-specific instructions, it is intended to optimize the execution of Java programs.

Applications of Java Programming Language

Understanding that Java is a flexible programming language with a wide variety of applications is crucial as an introduction to Java programming. 

  • Desktop Applications: Developers may construct cross-platform desktop apps with graphical user interfaces (GUI) using Java Swing and JavaFX frameworks.

  • Web Applications: Web applications frequently employ Java for server-side programming. Creating scalable and reliable online applications is possible with technologies like Java Servlets, JSF, and JSP and frameworks like Spring and Java EE.

  • Mobile Applications: Java is the main language for creating Android apps. Developers may use Java to create native Android applications by using the vast Android ecosystem.

  • Enterprise Applications: Java is the best platform for creating complex corporate applications because of its scalability and reliability. Java EE (now Jakarta EE) offers APIs and tools for distributed computing, database connection, and other enterprise features.

  • Embedded Systems: Java is appropriate for developing embedded systems, including Internet of Things (IoT) gadgets, smart cards, and other embedded software because of its platform independence and tiny footprint.


This tutorial provides a basic introduction to Java programming while emphasizing its main features and applications. Java is an advanced and adaptable programming language with various benefits, such as platform freedom, resilience, and an extensive library and framework ecosystem. Thanks to its comprehensive standard library and frameworks, developers can access a wide range of tools and resources for creating practical and feature-rich applications.

Java is still a dependable language for building robust software solutions because of its solid community support system and continual innovation. Java offers a strong foundation and limitless options for your projects, whether you're an experienced developer or a newbie just beginning your programming adventure.


  1. Is Java an interpreted language or a compiled one? 

When exploring the introduction to Java, it is compiled and interpreted. It is first compiled into bytecode and then interpreted by the Java Virtual Machine (JVM). 

  1. Is Java compatible with data science and machine learning? 

Yes, Java is capable of doing machine learning and data science jobs. Although Java has libraries like Weka and Deep learning for machine learning applications, other languages like Python are used more in these fields.

  1. What are the key features of Java? 

Java has many capabilities, including platform independence, object-oriented programming, automated memory management, multithreading, exception handling, and a sizable standard library. The adaptability and extensive use of Java is made possible by these qualities. 

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