Java Backend Development is a highly in-demand and well-paying job in the tech industry.

If you're looking to become an excellent Java Developer, here's a roadmap that includes various online resources:

1. Core Java

First comes the fundamentals of Java Programming, here you will understand OOP concepts, conditional statements, collection frameworks,and many more.

https://youtube.com/playlist?list=PLd3UqWTnYXOnjGmyjD3zbIkyLXP15-6w0&si=UYvQhVNlZQYCH1Il

2. JDBC

A  Java API that allows you to access tabular data, especially data stored in a relational database.

https://youtube.com/playlist?list=PLsyeobzWxl7rU7Jz3zDRpqB-EODzBbHOI&si=Cc45vpeRXGIUKbfn

3. SQL

Get a good understanding of SQL, which is necessary to work with JDBC to write queries.

https://youtu.be/7S_tz1z_5bA

4. JSP + Servlet

Learn JSP and Servlet, which are used for writing web pages for web applications and handling client requests on the server-side.

https://youtube.com/playlist?list=PLE0F6C1917A427E96&si=TQeOIgluG3R29622

5. Spring Framework

5.1. Core Spring Framework

https://youtu.be/GB8k2-Egfv0?si=dHYp6rFkGVl9RMt8

5.2. Spring REST & Spring DATA

https://youtu.be/GwYUjzPrQTM?si=hJfmpukii2WnofxQ

5.3. Spring Security
Spring Security is the primary choice for implementing application-level security

https://youtu.be/sm-8qfMWEV8?si=uMkpBxOUXIptZif9

6. Hibernate Framework

Hibernate is a Java framework that simplifies the development of Java application to interact with the database. It is an open source, lightweight, ORM (Object Relational Mapping) tool.

https://youtu.be/Yv2xctJxE-w?si=q4FIOBxxX-Y0Qj5q

7. Spring Boot

Spring Boot is the ultimate framework and Makes Java Web Development less boilerplate, it can help you make production-ready applications in no time.

https://youtu.be/msXL2oDexqw?si=XB19MCCECAggcB18

8. Basic DevOps

8.1. Learn to Use AWS & Deploy Java Apps

https://youtube.com/playlist?list=PLVz2XdJiJQxxurKT1Dqz6rmiMuZNdClqv&si=bJyg0Np11PkGDIKO

8.2. Learn Basic Docker:

https://youtu.be/p28piYY_wv8?si=Xoqje7MJad1NeE9g

8.3. Learn Basic Kubernetes:

https://youtu.be/rTNR7vDQDD8?si=dgzwxQof7yGHUP4n

8.4. Deploy Spring Boot App on Kubernetes:

https://youtu.be/EZolJ4lNiYc?si=Kw09qKwMp_LxHTvw

9. Basic of git and GitHub
https://youtu.be/apGV9Kg7ics?si=MHtCgD8o7XqpU4W3

10. Java Microservices

https://youtu.be/tuJqH3AV0e8?si=1jjrWl4l4uYGrE5i

14. Java Quick revision for Interviews

https://youtu.be/oYXivKMSEqM?si=tngbZrvgbAwsShEb

15. Spring JMS(java messaging services)

JMS is a standard Java API that allows a Java application to send messages to another application.

https://youtube.com/playlist?list=PLmCsXDGbJHdibOx6axScPiuHA8ftsrmut&si=J0qjBSbB4GDCeTOv

𝐉𝐨𝐢𝐧 𝐭𝐡𝐢𝐬 𝐭𝐞𝐥𝐞𝐠𝐫𝐚𝐦 𝐠𝐫𝐨𝐮𝐩 𝐟𝐨𝐫 𝐩𝐫𝐞𝐦𝐢𝐮𝐦 Resources/Notes: https://t.iss.one/udacityfreecourse

C++ va Java

Java Roadmap
|
|-- Fundamentals
| |-- Basics of Programming
| | |-- Introduction to Java
| | |-- Java Development Kit (JDK) and Java Runtime Environment (JRE)
| | |-- Setting Up Development Environment (IDE: IntelliJ IDEA, Eclipse, etc.)
| |
| |-- Syntax and Structure
| | |-- Basic Syntax
| | |-- Variables and Data Types
| | |-- Operators and Expressions
|
|-- Control Structures
| |-- Conditional Statements
| | |-- If-Else Statements
| | |-- Switch Case
| |
| |-- Loops
| | |-- For Loop
| | |-- While Loop
| | |-- Do-While Loop
| |
| |-- Exception Handling
| | |-- Try-Catch Block
| | |-- Finally Block
| | |-- Throw and Throws Keywords
|
|-- Object-Oriented Programming (OOP)
| |-- Basics of OOP
| | |-- Classes and Objects
| | |-- Methods and Constructors
| |
| |-- Inheritance
| | |-- Single and Multiple Inheritance
| | |-- Method Overriding
| | |-- Super Keyword
| |
| |-- Polymorphism
| | |-- Method Overloading
| | |-- Runtime Polymorphism
| | |-- Dynamic Method Dispatch
| |
| |-- Encapsulation
| | |-- Access Modifiers (Public, Private, Protected)
| | |-- Getters and Setters
| | |-- Data Hiding
| |
| |-- Abstraction
| | |-- Abstract Classes
| | |-- Interfaces
|
|-- Advanced Java
| |-- Collections Framework
| | |-- List (ArrayList, LinkedList)
| | |-- Set (HashSet, TreeSet)
| | |-- Map (HashMap, TreeMap)
| | |-- Queue (PriorityQueue, LinkedList)
| |
| |-- Concurrency
| | |-- Multithreading (Creating Threads, Thread Lifecycle)
| | |-- Synchronization
| | |-- Concurrency Utilities (Executors Framework, Callable and Future, Locks and Semaphores)
|
|-- Java Standard Libraries
| |-- I/O Streams
| | |-- File Handling (File Class, Reading and Writing Files)
| | |-- Streams (Byte Streams, Character Streams, Buffered Streams)
| |
| |-- Networking
| | |-- Sockets (TCP and UDP, Socket and ServerSocket Classes)
| | |-- URL and HTTP (URL Class, HttpURLConnection)
| |
| |-- JDBC
| | |-- Database Connectivity (JDBC Drivers, Connection, Statement, and ResultSet)
| | |-- PreparedStatement and CallableStatement
|
|-- Java Frameworks
| |-- Spring Framework
| | |-- Spring Core (Dependency Injection, Inversion of Control)
| | |-- Spring MVC (Model-View-Controller Architecture)
| | |-- Spring Boot (Creating Spring Boot Applications, Starters and Auto-Configuration, Actuator)
| |
| |-- Hibernate
| | |-- ORM Basics (Introduction to ORM, Configuration and Mapping)
| | |-- Advanced Hibernate (Caching, Transactions and Concurrency, Criteria API)
|
|-- Web Development with Java
| |-- Java EE (Jakarta EE)
| | |-- Servlets (Lifecycle, Handling HTTP Requests and Responses, Session Management)
| | |-- JavaServer Pages (JSP) (Syntax, Directives, JSTL and Custom Tags, Expression Language)
| |
| |-- RESTful Web Services
| | |-- JAX-RS (Creating RESTful Services, Annotations and HTTP Methods, Consuming RESTful Services)
|
|-- Build Tools and Dependency Management
| |-- Maven
| | |-- Project Object Model (POM), Dependencies, Repositories, Build Lifecycle and Plugins
| |
| |-- Gradle
| | |-- Build Scripts, Dependency Management, Task Automation
|
|-- Testing in Java
| |-- Unit Testing
| | |-- JUnit (Annotations, Assertions, Test Suites and Runners)
| |
| |-- Mockito (Creating Mocks and Spies and Verification)
| |
| |-- Integration Testing
| | |-- Spring Test (Testing Spring Components and WebTestClient)
|
|-- Deployment and DevOps
| |-- Containers and Microservices
| | |-- Docker (Dockerfile, Image Creation, Container Management)
| | |-- Kubernetes (Pods, Services, Deployments, Managing Java Applications on Kubernetes)

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https://t.iss.one/Java_Programming_Notes

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ENJOY LEARNING👍👍

Typical java interview questions sorted by experience


Junior
* Name some of the characteristics of OO programming languages
* What are the access modifiers you know? What does each one do?
* What is the difference between overriding and overloading a method in Java?
* What’s the difference between an Interface and an abstract class?
* Can an Interface extend another Interface?
* What does the static word mean in Java?
* Can a static method be overridden in Java?
* What is Polymorphism? What about Inheritance?
* Can a constructor be inherited?
* Do objects get passed by reference or value in Java? Elaborate on that.
* What’s the difference between using == and .equals on a string?
* What is the hashCode() and equals() used for?
* What does the interface Serializable do? What about Parcelable in Android?
* Why are Array and ArrayList different? When would you use each?
* What’s the difference between an Integer and int?
* What is a ThreadPool? Is it better than using several “simple” threads?
* What the difference between local, instance and class variables?

Mid
* What is reflection?
* What is dependency injection? Can you name a few libraries? (Have you used any?)
* What are strong, soft and weak references in Java?
* What does the keyword synchronized mean?
* Can you have “memory leaks” on Java?
* Do you need to set references to null on Java/Android?
* What does it means to say that a String is immutable?
* What are transient and volatile modifiers?
* What is the finalize() method?
* How does the try{} finally{} works?
* What is the difference between instantiation and initialisation of an object?
* When is a static block run?
* Why are Generics are used in Java?
* Can you mention the design patterns you know? Which of those do you normally use?
* Can you mention some types of testing you know?

Senior
* How does Integer.parseInt() works?
* Do you know what is the “double check locking” problem?
* Do you know the difference between StringBuffer and StringBuilder?
* How is a StringBuilder implemented to avoid the immutable string allocation problem?
* What does Class.forName method do?
* What is Autoboxing and Unboxing?
* What’s the difference between an Enumeration and an Iterator?
* What is the difference between fail-fast and fail safe in Java?
* What is PermGen in Java?
* What is a Java priority queue?
* *s performance influenced by using the same number in different types: Int, Double and Float?
* What is the Java Heap?
* What is daemon thread?
* Can a dead thread be restarted?

Source: medium.

GitHub Cheatsheet

What is Encapsulation in java ?

📍 Encapsulation is one of the fundamental principle of object oriented programming .
📍 Encapsulation allows to protect the data within a class from outside entities.
📍 Encapsulation helps to achieve hiding the internal information from outside entities.
📍 Data and methods (To access the data) are bundled together within a single unit .(class)
📍 In Java, encapsulation is typically achieved by:
Declaring the class members as private.
Providing public getter and setter methods to access and modify the private attributes.
Note :
Let's say we have 1 private variables in a class

Example - 1:
getter & setter for primitive type private members.
private String empnm;

// get method to access the data
public String GetName() {
return empnm;
}

// set the data
public void setName(String enm) {
this.empnm = enm;
} // call the method & pass the data as param

If we can notice the getter & setter for empnm , below points we can note:
1. getter method will return the variable which is private and it is non parameterized .
2. setter method is a parameterized method which we shall use to set the value for the private member while calling , so only it is parameterized method.

Example -2 :getter & Setter for the private array :

public int[] getarr() {
return arr;
}

// Setter method to modify the private array
public void setarr(int[] brr) {
// You can add validation or other logic if needed
this.arr = brr;
}

Best Programming Resources: https://topmate.io/coding/886839

All the best 👍👍

Typical java interview questions sorted by experience


Junior
* Name some of the characteristics of OO programming languages
* What are the access modifiers you know? What does each one do?
* What is the difference between overriding and overloading a method in Java?
* What’s the difference between an Interface and an abstract class?
* Can an Interface extend another Interface?
* What does the static word mean in Java?
* Can a static method be overridden in Java?
* What is Polymorphism? What about Inheritance?
* Can a constructor be inherited?
* Do objects get passed by reference or value in Java? Elaborate on that.
* What’s the difference between using == and .equals on a string?
* What is the hashCode() and equals() used for?
* What does the interface Serializable do? What about Parcelable in Android?
* Why are Array and ArrayList different? When would you use each?
* What’s the difference between an Integer and int?
* What is a ThreadPool? Is it better than using several “simple” threads?
* What the difference between local, instance and class variables?

Mid
* What is reflection?
* What is dependency injection? Can you name a few libraries? (Have you used any?)
* What are strong, soft and weak references in Java?
* What does the keyword synchronized mean?
* Can you have “memory leaks” on Java?
* Do you need to set references to null on Java/Android?
* What does it means to say that a String is immutable?
* What are transient and volatile modifiers?
* What is the finalize() method?
* How does the try{} finally{} works?
* What is the difference between instantiation and initialisation of an object?
* When is a static block run?
* Why are Generics are used in Java?
* Can you mention the design patterns you know? Which of those do you normally use?
* Can you mention some types of testing you know?

Senior
* How does Integer.parseInt() works?
* Do you know what is the “double check locking” problem?
* Do you know the difference between StringBuffer and StringBuilder?
* How is a StringBuilder implemented to avoid the immutable string allocation problem?
* What does Class.forName method do?
* What is Autoboxing and Unboxing?
* What’s the difference between an Enumeration and an Iterator?
* What is the difference between fail-fast and fail safe in Java?
* What is PermGen in Java?
* What is a Java priority queue?
* *s performance influenced by using the same number in different types: Int, Double and Float?
* What is the Java Heap?
* What is daemon thread?
* Can a dead thread be restarted?

Source: medium.

Java for Everything: ☕

Java + Spring = Enterprise Applications

Java + Hibernate = Object-Relational Mapping

Java + Android = Mobile App Development

Java + Swing = Desktop GUI Applications

Java + JavaFX = Modern GUI Applications

Java + JUnit = Unit Testing

Java + Maven = Project Management

Java + Jenkins = Continuous Integration

Java + Apache Kafka = Stream Processing

Java + Apache Hadoop = Big Data Processing

Java + Microservices = Scalable Services

Best Programming Resources: https://topmate.io/coding/886839

All the best 👍👍

Top 10 String Programs for Java Interview

Learn for Full Stack Web Dev for Free ⚡

🔺HTML-> w3schools
🔺CSS -> freeCodeCamp
🔺Javascript -> @javascript_courses
🔺NodeJS -> freeCodeCamp
🔺ExpressJS -> MDN
🔺MongoDB -> MDB University
🔺REST APIs -> Postman
🔺Git -> learnGitBranching
🔺Deployment -> Firebase

Websites to learn Java

Java is a popular programming language that is widely used for developing various types of applications, including web applications, mobile apps, desktop applications, and enterprise systems. Here are some key concepts to understand the basics of Java:

1. Object-Oriented Programming (OOP): Java is an object-oriented programming language, which means it focuses on creating objects that contain both data and methods to operate on that data. Key principles of OOP in Java include encapsulation, inheritance, and polymorphism.

2. Classes and Objects: In Java, a class is a blueprint for creating objects. An object is an instance of a class that represents a real-world entity. Classes define the properties (attributes) and behaviors (methods) of objects.

3. Variables and Data Types: Java supports various data types, including primitive data types (e.g., int, double, boolean) and reference data types (e.g., String, arrays). Variables are used to store data values in memory.

4. Methods: Methods in Java are functions defined within a class to perform specific tasks. They encapsulate behavior and can accept parameters and return values.

5. Control Flow Statements: Java provides control flow statements such as if-else, switch-case, loops (for, while, do-while), and break/continue statements to control the flow of program execution.

6. Inheritance: Inheritance is a key feature of OOP that allows a class (subclass) to inherit properties and behaviors from another class (superclass). It promotes code reusability and establishes an "is-a" relationship between classes.

7. Polymorphism: Polymorphism allows objects of different classes to be treated as objects of a common superclass. It enables methods to be overridden in subclasses to provide different implementations.

8. Abstraction: Abstraction involves hiding the complex implementation details and showing only the essential features of an object. Abstract classes and interfaces are used to achieve abstraction in Java.

9. Encapsulation: Encapsulation is the process of bundling data (attributes) and methods that operate on that data within a class. It helps in data hiding and protects the internal state of an object.

10. Exception Handling: Java provides mechanisms for handling exceptions that occur during program execution. The try-catch-finally blocks are used to handle exceptions gracefully and prevent program crashes.

Understanding these basic concepts of Java will help you get started with programming in Java. Practice writing Java programs, exploring different features of the language, and building small projects to strengthen your Java skills.

Java projects 👇