Ultimate Guide to Java Virtual Threads: Build Scalable Applications with Ease

Are Java Virtual Threads the Future of Concurrency? Absolutely. Here's Why You Should Care.

If you're a Java developer, you already know: every line of code runs on a thread. Threads are the fundamental unit of scheduling and concurrency in any Java application.

Traditionally, developers have relied on multiple OS-level threads to handle concurrent tasks. For example, Spring Boot with embedded Tomcat comes configured with 200 threads by default, allowing it to process up to 200 concurrent requests. Sounds powerful, right?

But here’s the catch...

🧠 Why Traditional Threads Limit Scalability

Each request in a Java web application is processed by a dedicated OS thread. If each request takes 1 second, a 200-thread system can handle 200 requests per second — that’s your application throughput.

So, why not just add more threads?

Because OS threads are heavyweight:

Each thread consumes significant memory.

The OS has limits on how many threads can be created.

Managing thousands of threads leads to context switching overhead, degrading performance.

That’s where Java Virtual Threads come into play — a game-changing concurrency model introduced in Project Loom.

Mastering @JsonFormat in Jackson: A Complete Guide with Examples

If you're working with Java and JSON, the Jackson library is likely part of your tech stack. One of the most powerful yet underused annotations it provides is @JsonFormat.

In this ultimate guide, we’ll break down what @JsonFormat does, when to use it, and how to handle advanced scenarios with fully working examples. This post is optimized for SEO to help developers find quick and accurate answers.

✅ What is @JsonFormat in Jackson?

@JsonFormat is a Jackson annotation that helps control how Java fields are serialized (Java to JSON) or deserialized (JSON to Java). This is especially useful for dates, enums, and number formats.

Import Statement:

import com.fasterxml.jackson.annotation.JsonFormat;

Dependencies

Make sure you include the correct Jackson modules for java.time:

 <dependency>
   <groupId>com.fasterxml.jackson.datatype</groupId>
   <artifactId>jackson-datatype-jsr310</artifactId>
   <version>2.15.3</version>
 </dependency>
 

And register it:

 ObjectMapper mapper = new ObjectMapper();
 mapper.registerModule(new JavaTimeModule());
 

Java Program To Reverse A String Without Using String Inbuilt Function reverse()

1. Introduction

In this tutorial, You'll learn how to write a java program to reverse a string without using string inbuilt function reverse().
This is a very common interview question that can be asked in many forms as below.

A) java program to reverse a string without using string inbuilt function
B) java program to reverse a string using recursion
C) java program to reverse a string without using the reverse method
C) Try using other classes of Java API (Except String).



The interviewer's main intention is not to use the String class reverse() method.

Anonymous Comparator In Java For Sorting

1. Overview

In this tutorial, We'll learn how to sort arrays or lists using an anonymous comparator in java.

A complete guide on how to use comparator in java?

Anonymous class means creating the class and providing the implementation at the same without a class name.

For example, we have an interface Job and it has the method post() to post the new job. here, a new job1 instance is created for the implementation class of Job interface without a class name.

Example 1

interface Job {
	void post();
}

Job job1 = new Job() {

	@Override
	public void post() {
		System.out.println("Posting job 1 now");

}

This is similar to the anonymous implementation of the abstract class or interface. This is the actual implementation of the Comparator without creating a class and implementing the Comparator interface.