Java Tutorial



Java Tutorial

What is Java?

Java, a programming language valued for its versatility and extensive use, is known for its resilience and ability to function on different platforms. It boasts a user-friendly syntax and a vast collection of libraries, making it suitable for a broad range of applications.

Java’s principle of being able to write code once and run it on multiple platforms without recompiling contributes to its immense popularity. 


This tutorial is for beginner-level programmers interested in web development, mobile apps, or enterprise solutions. It is a holistic guide about what is Java, what is Java programming used for, and about Java development that provides a dependable foundation for crafting efficient and powerful software.

What is Java?

Java is a widely-used programming language valued for its versatility and robustness. It is known for its platform independence, user-friendly syntax, and extensive library collection, making it suitable for various applications. The "write once, run anywhere" principle allows Java programs to operate on multiple platforms without recompilation. 

Java's object-oriented nature promotes the creation of reusable and modular code, enabling the development of scalable and easily maintainable software solutions. Whether web development, mobile applications, or enterprise systems, Java provides a strong foundation for building efficient and potent software.

History of Java

Java originated in the 1990s as a programming language and platform developed by Sun Microsystems. James Gosling led the team with the goal of creating a versatile language capable of functioning on diverse devices. Initially known as "Oak," it was renamed "Java" due to trademark concerns. 

Java was officially introduced in 1995 and gained popularity for its unique "write once, run anywhere" concept, enabling code execution across different platforms. The acquisition of Sun Microsystems by Oracle Corporation in 2010 ensured Java's continuous support and development. Through subsequent versions and updates, Java has remained a highly prevalent programming language worldwide.

What is Java Programming Used For?

Java is a highly adaptable programming language used across diverse industries. Its application extends to web development, powering dynamic websites, e-commerce platforms, and enterprise applications. Leading web frameworks like Spring, JavaServer Faces (JSF), and JavaServer Pages (JSP) utilize Java to deliver scalable and interactive web solutions. 

In the mobile app domain, Java is the primary language for Android app development, leveraging its extensive Android SDK libraries to create feature-rich mobile experiences. Java also finds extensive usage in enterprise software development, facilitating the creation of robust systems like CRM software, ERP systems, and financial management solutions. 

Additionally, Java is pivotal in scientific research, data analysis, and machine learning projects. Given its versatility and extensive ecosystem, Java remains a preferred choice for various applications and industries.

What is Java Based Upon?

Java is derived from a blend of programming languages and concepts. Its syntax is reminiscent of C and C++, ensuring familiarity for those well-versed in those languages. Drawing inspiration from Smalltalk, Java embraces the principles of object-oriented programming (OOP). 

The design of Java's virtual machine (JVM), which grants platform independence, takes cues from the UCSD Pascal system. Additionally, Java integrates certain features from different programming languages. 

For instance, garbage collection techniques were influenced by Lisp, while the concept of strong typing originated from Ada. By amalgamating diverse elements, Java presents a distinct composition and functionality that sets it apart.

Editions in Java

Java comes in different editions to cater to various programming needs. These different editions allow developers to choose the appropriate Java version based on their specific programming requirements.

Java Standard Edition  

Java Standard Edition (Java SE) is a fundamental edition of Java designed to meet the programming needs of various applications. It offers a comprehensive range of libraries, tools, and APIs that assist developers in creating software for desktop, server, and standalone environments. With Java SE, developers can access a rich set of resources that support application development on multiple platforms.

Java Enterprise Edition

Java Enterprise Edition (Java EE) focuses on enterprise-level development, offering a robust platform for large-scale, distributed applications. It provides additional features and libraries tailored for web and enterprise development.

Java Micro Edition 

Java Micro Edition (Java ME) targets resource-constrained devices like mobile phones and embedded systems. It provides a stripped-down version of Java optimized for devices with limited resources. Java ME enables developers to create Java-based applications for small-scale, low-power devices. 

Java Concept and Features

Java Concepts


In Java, an object represents a real-world entity and serves as the fundamental building block of a Java program. It embodies both state (data) and behavior (methods).


A class acts as a blueprint or template for creating objects. It defines the characteristics (data) and actions (methods) that objects of that class will possess.


A constructor is a special method used to initialize objects of a class. It is automatically invoked during object creation and helps set initial values to the object's data members.


Inheritance allows the creation of a new class (subclass) by inheriting properties and behaviors from an existing class (superclass). It promotes code reuse and supports the concept of hierarchical relationships between classes.


Polymorphism enables objects of different classes to be treated as objects of a common superclass. It allows methods to be overridden in subclasses, facilitating the implementation of different behaviors for objects of different types.


Abstraction focuses on creating abstract classes or interfaces that define common properties and behaviors without providing specific implementation details. It allows for the creation of generalized frameworks that concrete classes can extend.


Encapsulation combines data and methods within a class, protecting the data from external access. It ensures data integrity and provides control over data manipulation through access modifiers.

Features of Java

Platform Independence

Java programs can run on any platform thanks to the JVM (Java Virtual Machine), which is an intermediary between the code and the underlying operating system.


Java follows an object-oriented programming (OOP) paradigm, placing emphasis on the use of objects and classes to structure code and promote code reuse and modularity.

Memory Management

Java automates memory management through garbage collection, relieving developers from manual memory allocation and deallocation.

Exception Handling

Java provides built-in mechanisms for handling runtime errors and exceptions, allowing developers to handle them gracefully and ensure program stability.


Java supports concurrent programming through multi-threading, enabling multiple threads of execution to run simultaneously within a single program.

Standard Library

Java offers a comprehensive standard library (Java API) with pre-built classes and utilities for various tasks, such as input/output operations, networking, database connectivity, and more.


Java incorporates robust security features, including bytecode verification, sandboxing, and cryptography libraries, making it a secure programming language for application development.


Java supports dynamic programming features, allowing dynamic class loading, reflection, and runtime code execution, providing flexibility and adaptability in software development.

Components of Java


JVM (Java Virtual Machine) is a crucial element of the Java platform. It is a virtual machine that executes compiled Java bytecode, enabling Java programs to run independently across different hardware and operating systems. JVM handles essential tasks like memory management, garbage collection, and bytecode interpretation or just-in-time (JIT) compilation.


JRE (Java Runtime Environment) is a software bundle encompassing the necessary runtime libraries, class libraries, and JVM implementation. It offers the runtime environment required to execute Java applications, ensuring their proper functioning. However, JRE does not include the tools needed for Java development.


JDK (Java Development Kit) is a comprehensive software development kit that includes all the essential tools, libraries, and documentation for Java development. It provides a complete development environment, including the JRE and additional tools like the Java compiler (javac), debugger (jdb), and various utilities.

Java OOPs Concepts


Abstraction is a fundamental principle in object-oriented programming (OOP) that emphasizes creating abstract classes or interfaces to define common characteristics and behaviors without specifying implementation details. This enables the development of flexible frameworks that can be extended by specific classes, promoting code organization and reuse.


Encapsulation involves grouping data (attributes) and methods (behaviors) within a class, shielding internal details, and preventing direct external access. It bundles related data and methods, ensuring data integrity and regulating data manipulation using access modifiers.


Polymorphism allows objects of different classes to be treated as objects of a shared superclass. It enables the customization of methods in subclasses, allowing objects of varying types to exhibit different behaviors. Polymorphism enhances code flexibility, promotes extensibility, and improves program readability and maintenance.


Inheritance is a mechanism in OOP that enables the creation of new classes (subclasses) by inheriting properties and behaviors from existing classes (superclasses). Subclasses inherit attributes and methods from their superclasses, facilitating code reuse and establishing hierarchical relationships between classes. Inheritance facilitates the development of specialized classes that inherit and expand upon the functionality of their parent classes.

How to Learn Java?

Learning programming initially entails knowing about what is Java development. To embark on your Java learning journey as a beginner:

  • Learn the basics: Familiarize yourself with the basics, such as variables, data types, and control structures like if-else statements and loops.

  • Practice code: Apply your knowledge by writing simple programs to reinforce your understanding. Dedicate consistent time to practice and experiment, as it will progressively enhance your skills.

  • Learn object-oriented programming: Consider upskilling yourself with knowledge about classes, objects, inheritance, and polymorphism.

  • Use online resources: Multiple tutorials, videos, and interactive platforms offer hands-on practice opportunities.

  • Develop personal projects: Put your skills to the test by creating small projects that allow you to gain practical experience.


Java programming provides developers a versatile and reliable platform supported by a thriving ecosystem. It remains a prominent language for building scalable software solutions in diverse domains. You can unlock your coding potential to create groundbreaking applications that shape the digital landscape by enrolling in top-tier programming courses from upGrad.


1. What is a Java developer?

A Java developer is a professional who specializes in programming and developing applications using the Java programming language.

2. What are Java interview questions?

Java interview questions are commonly asked to assess a candidate's knowledge and proficiency in Java programming. They cover topics like syntax, object-oriented concepts, exception handling, and Java APIs.

3. What are Java and javascript?

Java is a widely used programming language known for its platform independence, primarily for building desktop, web, and enterprise applications. On the other hand, JavaScript is a scripting language used for creating dynamic and interactive elements within web browsers. 

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