Java Tutorials

Concurrent Collections in Java

🚨 The Problem with Standard Collections In multithreaded environments, using standard collections like ArrayList, HashMap, or HashSet can lead to data corruption, inconsistent state, or ConcurrentModificationException. Example Problem: List<String> list...

Concurrent Collections in Java

🚨 The Problem with Standard Collections In multithreaded environments, using standard collections like ArrayList, HashMap, or HashSet can lead to data corruption, inconsistent state, or ConcurrentModificationException. Example Problem: List<String> list...

🧩 Generics in Java – Type-Safe Code Simplified

What are Generics? Generics in Java allow you to write type-safe and reusable code by enabling classes, interfaces, and methods to operate on objects of various types while providing compile-time type...

🧩 Generics in Java – Type-Safe Code Simplified

What are Generics? Generics in Java allow you to write type-safe and reusable code by enabling classes, interfaces, and methods to operate on objects of various types while providing compile-time type...

Spring Boot & MongoDB integration

A Spring Boot REST API that connects to MongoDB, performs CRUD operations, and uses Spring Data MongoDB. 🧱 1. Maven Dependencies <!-- Spring Boot Starter for MongoDB --><dependency>  <groupId>org.springframework.boot</groupId>  <artifactId>spring-boot-starter-data-mongodb</artifactId></dependency> <!--...

Spring Boot & MongoDB integration

A Spring Boot REST API that connects to MongoDB, performs CRUD operations, and uses Spring Data MongoDB. 🧱 1. Maven Dependencies <!-- Spring Boot Starter for MongoDB --><dependency>  <groupId>org.springframework.boot</groupId>  <artifactId>spring-boot-starter-data-mongodb</artifactId></dependency> <!--...

Lambda Sample Examples

✅ 1. Lambda with No Parameters Runnable greet = () -> System.out.println("Hello from Lambda!");greet.run(); ✅ 2. Lambda with One Parameter Consumer<String> printer = name -> System.out.println("Welcome, " + name);printer.accept("Aftab"); ✅...

Lambda Sample Examples

✅ 1. Lambda with No Parameters Runnable greet = () -> System.out.println("Hello from Lambda!");greet.run(); ✅ 2. Lambda with One Parameter Consumer<String> printer = name -> System.out.println("Welcome, " + name);printer.accept("Aftab"); ✅...

Stream API Sample Examples

✅ 1. Filter Even Numbers List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6); List<Integer> evens = numbers.stream()                         ...

Stream API Sample Examples

✅ 1. Filter Even Numbers List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6); List<Integer> evens = numbers.stream()                         ...

🔹 What is Optional?

Optional<T> is a container object that may or may not hold a non-null value. ✅ It’s a wrapper around an object that helps you write null-safe code. 🧱 Why Use...

🔹 What is Optional?

Optional<T> is a container object that may or may not hold a non-null value. ✅ It’s a wrapper around an object that helps you write null-safe code. 🧱 Why Use...