Java Tutorials

Fresh Java lessons, interview questions, examples, and project notes for beginners and working developers. Start with basics, then move into OOP, collections, Java 8, JDBC, Spring Boot, and real project practice.

Java Learning Path

Beginner to job-ready
  1. 1. Core SyntaxVariables, data types, operators, loops, methods, arrays.
  2. 2. OOPClasses, objects, inheritance, abstraction, interfaces, packages.
  3. 3. Standard LibraryStrings, collections, dates, files, exceptions, generics.
  4. 4. Backend SkillsJDBC, Maven, REST APIs, Spring Boot, testing, deployment.

Core Java Tutorials

Most-read topics

  • Java Basics Roadmap

    Learn variables, primitive types, strings, operators, conditionals, loops, methods, arrays, and input/output.

    • Hello World program
    • if/else and switch
    • for, while, do-while loops

  • Object-Oriented Programming

    Understand classes, objects, inheritance, abstraction, interfaces, packages, and reusable code design.

    • Class and object
    • Constructor and this keyword
    • Inheritance and polymorphism

  • Java Collections Framework

    Use List, Set, Map, Queue, iterators, sorting, comparable, comparator, and common collection patterns.

    • ArrayList vs LinkedList
    • HashMap vs TreeMap
    • HashSet vs LinkedHashSet

  • Exception Handling

    Write safer programs with try/catch/finally, custom exceptions, checked exceptions, and runtime exceptions.

    • throw vs throws
    • Custom exception class
    • Best practices

  • Java 8 Features

    Practice lambdas, streams, Optional, method references, functional interfaces, and default methods.

    • Stream filter and map
    • Optional examples
    • Predicate and Function

Java Program Example

A simple class with a method, loop, and output.

public class Main {
    public static void main(String[] args) {
        String language = "Java";

        for (int i = 1; i <= 3; i++) {
            System.out.println(i + ". Learn " + language);
        }
    }
}

Java Interview Practice

  • What is the difference between JDK, JRE, and JVM?
  • Why is Java platform independent?
  • What is method overloading and overriding?
  • How does HashMap work internally?
  • What is the difference between checked and unchecked exceptions?
  • What are functional interfaces in Java?

Advanced Java and Backend

Next step topics

  • JDBC and MySQL

    Connect Java applications to MySQL, run SQL queries, use prepared statements, and handle result sets.

  • Maven Project Setup

    Create Maven projects, manage dependencies, configure plugins, and organize source folders correctly.

  • JUnit Testing

    Write unit tests for Java methods, use assertions, test edge cases, and structure test classes.

  • Spring Boot Basics

    Build REST controllers, services, repositories, DTOs, validation, and exception handling flows.

  • REST API Project

    Create a CRUD API for students, products, or employees using Spring Boot and MySQL.

  • Java Mini Projects

    Practice with console apps, file handling tools, quiz apps, billing systems, and library management.

Recommended Java Project Ideas

  • Student Management System using Core Java and file handling.
  • Bank Account App with OOP, custom exceptions, and transaction history.
  • Employee CRUD App using JDBC and MySQL.
  • Quiz Application with score tracking and category-based questions.
  • Spring Boot REST API for products, categories, and orders.
  • Blog API with users, posts, comments, validation, and pagination.