Welcome to Java Stash: Your Free Java Learning Hub

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Basics

Introduction

Java is a robust object-oriented language for web and enterprise applications.

Installation

Java installation uses JDK for development with IDEs like IntelliJ.

Running Code

Java code runs via javac and java commands with .java files.

Syntax

Java syntax uses semicolons and curly braces with strong typing.

Variables

Java variables use explicit types or var with final for immutability.

Data Types

Java data types include int String and boolean with primitives.

Type Inference

Java type inference uses var for local variables since Java 10.

Null Handling

Java null handling uses Optional to avoid NullPointerExceptions.

Operators

Java operators include arithmetic and logical with precedence rules.

If Else

Java if-else statements control flow with pattern matching.

Switch

Java switch expressions handle cases with yield since Java 14.

Loops

Java loops use for foreach and while with break and continue.

Comments

Java comments use // and /* */ with Javadoc for APIs.

Errors

Java errors use try-catch with checked and unchecked exceptions.

Debugging

Java debugging uses IntelliJ or Eclipse with breakpoints.

Best Practices

Java best practices include null avoidance, immutable objects.

Security Basics

Java security ensures safe input handling with validation.

Packages

Java packages organize code with import statements.

Maven

Java Maven manages dependencies with pom.xml for builds.

System.out

Java System.out.println outputs to console with formatting.

Methods

Java methods use typed parameters and return types.

Lambda Expressions

Java lambda expressions use -> for functional interfaces.

Anonymous Classes

Java anonymous classes implement interfaces inline.

Method References

Java method references use :: for concise lambda syntax.

Functional Interfaces

Java functional interfaces enable lambda with @FunctionalInterface.

Async Methods

Java async methods use CompletableFuture for non-blocking calls.

Generic Methods

Java generic methods use <T> for type-safe polymorphism.

Classes

Java classes use class with fields and methods.

Interfaces

Java interfaces define contracts with default methods since Java 8.

Inheritance

Java inheritance uses extends for single inheritance.

Abstract Classes

Java abstract classes define blueprints with abstract methods.

Enums

Java enums define constants with methods and fields.

Records

Java records provide immutable data since Java 14.

Annotations

Java annotations add metadata with @ for frameworks.

Arrays

Java arrays are fixed-length typed collections with indexing.

Lists

Java lists use ArrayList or LinkedList for dynamic collections.

Maps

Java maps use HashMap for key-value pairs.

Sets

Java sets use HashSet for unique elements.

Queues

Java queues use LinkedList or PriorityQueue for FIFO.

Streams

Java Streams process collections with functional operations.

Threads

Java Threads enable concurrency with Thread class or Runnable.

CompletableFuture

Java CompletableFuture handles async tasks with thenApply.

ExecutorService

Java ExecutorService manages thread pools for tasks.

Synchronized

Java synchronized ensures thread-safe access with locks.

Concurrent Collections

Java concurrent collections like ConcurrentHashMap ensure thread safety.

File Reading

Java file reading uses Files.readString with try-catch.

File Writing

Java file writing uses Files.writeString with buffered streams.

File Paths

Java file paths use Path for cross-platform handling.

File Deletion

Java file deletion uses Files.delete with error handling.

HTTP Server

Java HTTP server uses Spring Boot or Jakarta EE for web apps.

HTTP Client

Java HTTP client uses HttpClient for API calls since Java 11.

HTTP Routing

Java HTTP routing uses Spring Boot for endpoints.

JSON Handling

Java JSON handling uses Jackson or Gson for serialization.

JSON Serialization

Java JSON serialization uses ObjectMapper with POJOs.

JSON Deserialization

Java JSON deserialization uses ObjectMapper with typed classes.

Spring Boot

Java Spring Boot builds scalable web apps with MVC and REST.

Jakarta EE

Java Jakarta EE provides enterprise APIs for web and microservices.

REST APIs

Java REST APIs use Spring Boot with JSON responses.

GraphQL APIs

Java GraphQL APIs use graphql-java for typed queries.

WebSockets

Java WebSockets use Spring WebSocket for real-time apps.

Authentication

Java authentication uses Spring Security or JWT for APIs.

Environment Variables

Java environment variables use System.getenv for config.

CORS

Java CORS enables cross-origin requests with Spring middleware.

Hibernate

Java Hibernate maps database queries to objects with JPA.

SQL Server

Java SQL Server uses JDBC or Hibernate for queries.

PostgreSQL

Java PostgreSQL uses JDBC with PgJDBC for typed queries.

MongoDB

Java MongoDB uses MongoDB Java Driver for document data.

Database Transactions

Java database transactions use Hibernate for atomicity.

Logging

Java logging uses SLF4J or Log4j for structured logs.

Error Logging

Java error logging captures exceptions with Log4j.

Request Logging

Java request logging tracks API calls with Spring middleware.

Testing

Java testing uses JUnit or TestNG with Maven or Gradle.

Unit Testing

Java unit testing uses Assertions for function validation.

Integration Testing

Java integration testing validates APIs with Spring Test.

Mocking

Java mocking uses Mockito for isolated unit tests.

Benchmarking

Java benchmarking uses JMH for performance tests.

REST API

Java REST API with Spring Boot handles CRUD with JSON.

Authentication API

Java authentication API uses JWT for secure endpoints.

Database CRUD

Java database CRUD with Hibernate handles data operations.

Real-Time Chat

Java real-time chat uses Spring WebSocket for messaging.

Spring Boot App

Java Spring Boot app creates web UIs with MVC.

API Testing

Java API testing with Spring Test validates REST endpoints.

Logging Setup

Java logging setup with Log4j logs requests and errors.

Dockerized App

Java Dockerized app uses Dockerfile for deployment.

Hibernate Query

Java Hibernate query retrieves data with HQL expressions.

WebSocket App

Java WebSocket app uses Spring for real-time communication.

Java Annotation Analyzer

This page provides the Java Annotation Analyzer tool. Utilize it for your tasks.

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Java Code Commenter

This page provides the Java Code Commenter tool. Utilize it for your tasks.

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Java Code Formatter

This page provides the Java Code Formatter tool. Utilize it for your tasks.

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Java Error Explainer

This page provides the Java Error Explainer tool. Utilize it for your tasks.

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Java Javadoc Generator

This page provides the Java Javadoc Generator tool. Utilize it for your tasks.

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Java Standard Library Reference

This page provides the Java Standard Library Reference tool. Utilize it for your tasks.

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Java Stream API Explainer

This page provides the Java Stream API Explainer tool. Utilize it for your tasks.

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Java to Kotlin Converter Preview

This page provides the Java to Kotlin Converter Preview tool. Utilize it for your tasks.

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Welcome to Java Stash: Your Free Java Learning Hub

Basics

Functions

Classes

Data Structures

Concurrency

File I/O

HTTP

JSON

Web Development

Databases

Logging

Testing

Examples

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