How do I compile and run these Java programs?

Install a JDK, compile with javac Main.java, then run with java Main.

Which Java version are these examples compatible with?

Examples target Java 8+, including lambdas and streams.

Can I safely copy and modify the examples?

Yes. Copy, modify inputs, and observe outputs to reinforce concepts.

Do these programs work on all platforms?

Programs compile and run on Windows, macOS, and Linux with a standard JDK.

Object-Oriented Patterns: Classes, Interfaces, Inheritance

Create classes and interfaces, use inheritance and abstract types. Understand how Java models objects and promotes reusable, maintainable code.

Java Program with Interface Implementation

Program (Java)

Example & Expected Output

Implements a simple interface.

28.27

Program Output

Java Program: Class and Object Basics

Program (Java)

Example & Expected Output

Defines a simple class and creates an object.

Hello, Alice

Program Output

Java Program Demonstrating Inheritance

Program (Java)

Example & Expected Output

Shows a subclass extending a base class.

Woof

Program Output

Java Program with Abstract Class

Program (Java)

Example & Expected Output

Demonstrates abstract class and method.

Program Output

Java Program to Reverse a String

Program (Java)

Example & Expected Output

Reverses a string using StringBuilder.

avaJ

Program Output

Frequently Asked Questions

Install a JDK (Java Development Kit), then compile with javac Main.java and run with java Main. On macOS, Linux, or Windows, use the official OpenJDK builds or your package manager.

The examples target modern Java (Java 8 and above). If you use older versions, most examples will still work, but features like lambdas and streams require Java 8+.

Yes. These examples are intended for learning. Copy the code, experiment with changes (e.g., different inputs), and observe the output to deepen your understanding of Java fundamentals.

Yes. Java is platform-independent. The examples compile and run on major platforms (Windows, macOS, Linux) with a standard JDK.

Learn Java the Practical Way

Java powers enterprise applications, Android development, and countless backend systems. Practicing small, focused programs builds fluency with syntax and core concepts such as data types, control flow, methods, classes, interfaces, exceptions, collections, and streams.

On this page, you will find clean, well-formatted examples that run across platforms. Each example includes a short description and expected output so you can quickly verify your understanding. Explore the topics via the sidebar and extend the code to experiment further.

Whether you are preparing for interviews, working through coursework, or refreshing fundamentals, these examples offer a practical path to mastering Java. Bookmark the page and return often to keep improving.