Author Archives: paulsofts

Concurrent HashMap – Real life use of Concurrent HashMap

By | June 26, 2024
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What is ConcurrentHashMap? In Java, ConcurrentHashMap is a class that implements the Map<K,V> interface, and it is synchronised. When we declare a HashMap<K,V> in Java, the JVM internally assigns 16 buckets of memory to it. In ConcurrentHashMap, the lock is on each of the 16 buckets, which facilitates multiple write operations on different buckets concurrently… Read More: Concurrent HashMap – Real life use of Concurrent HashMap »

Java interview questions for 5 years experience – Java developer interview questions & answer

By | January 27, 2025
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Java Interview Questions

1. String vs. StringBuilder | When to use String and StringBuilder in Java? Feature String StringBuilder Definition String is an immutable class in Java, which means once an object is created, its value cannot be changed. StringBuilder is used to create mutable string objects, which means we can change the content of the StringBuilder object.… Read More: Java interview questions for 5 years experience – Java developer… »

How to resolve CORS issue in Angular? | origin ‘http://localhost:4200’ has been blocked by cors policy: response to preflight request doesn’t pass access control check

By | September 19, 2024
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CORS stands for Cross-Origin Resource Sharing, a security feature that is implemented by web browsers to protect users from malicious websites that try to access data on another domain without permission. It occurs when an application attempts to make a request to a different domain than the one that served the application. In an Angular… Read More: How to resolve CORS issue in Angular? | origin ‘http://localhost:4200’… »

Real time weather app using Angular 17

By | September 5, 2024
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Real time weather app using Angular 17

Angular is an open-source, Typescript based web application framework that runs on Node.js. In this article, we’ll learn how to create a real time weather app using Angular that retrieves weather information based on the name of the city. Steps to build real time weather app Step 1- How to create angular project in Visual… Read More: Real time weather app using Angular 17 »

Publish Subscribe Messaging system

By | September 3, 2024
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Publish Subscribe Messaging system

In the publish-subscribe messaging system, each message has multiple consumers. Topics are based on a publish subscribe messaging model where each message is broadcast to multiple subscribers who are listening to the topic. Key feature of Publish Subscribe messaging model When to use publisher subscribe messaging model The publish-subscribe messaging model should be used when… Read More: Publish Subscribe Messaging system »

What is JMS? | Java Message Service [2025]

By | December 14, 2025
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What is JMS

What is Java Messaging Service (JMS)? The Java Message Service (JMS) is a messaging standard (API) that allows Java applications to create, send, and receive messages asynchronously and reliably. It provides a common interface for different messaging providers, promoting loose coupling between clients and systems. This guide simplifies JMS core concepts with practical examples. Why… Read More: What is JMS? | Java Message Service [2025] »

What is Circular dependency in Spring Boot?

By | September 6, 2024
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What is Dependency? When a class or object depends on another class or object for its functioning, it is called dependency. For example, Say we have two classes: company and employee, and the company class needs employees to work. We can say that company class depends on the employee. What is Circular Dependency? When we… Read More: What is Circular dependency in Spring Boot? »

Apache Kafka producer consumer example using Kafka console

By | June 18, 2025
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Apache Kafka producer consumer example using Kafka console

Kafka producers are those that publish the message to the Kafka topics, and Kafka consumers consume those messages by subscribing to the Kafka topics. To learn more, please refer Apache Kafka Architecture. In this tutorial, we will learn to create a producer-consumer model using the Kafka console. In this tutorial, we will learn about Kafka… Read More: Apache Kafka producer consumer example using Kafka console »

What will happen if the AUTO_INCREMENT ID column reaches its maximum value? (Github Outage Issue)

By | March 16, 2024
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On May 5, 2020, the auto-incrementing ID column in a shared database table on Github grew larger than what the MySQL integer type could handle. The github-blog page has all of the incident’s information. We will simulate the situation in which we force the value of our auto-increment ID column in the MySQL database to… Read More: What will happen if the AUTO_INCREMENT ID column reaches its… »