Sorting a list of strings in Java is straightforward — and you can do it in several ways, depending on whether you want natural order, reverse order, or a custom comparator. Here’s a complete guide 👇 ✅ 1. Sort in Natural (Alphabetical) Order import java.util.*; public class SortStringsExample { public static void main(String[] args)…
In Java, the volatile keyword is used to indicate that a variable’s value may be changed by multiple threads, and that all threads should always see the most up-to-date value of that variable. It’s a key concept in multithreading and concurrency. 🧠 Definition A volatile variable is one whose reads and writes go directly…
In JUnit (Java Unit Testing framework), annotations are special markers (prefixed with @) that tell JUnit how to run and organize your tests. Let’s go over the most important JUnit annotations — for both JUnit 4 and JUnit 5 (Jupiter). 🧪 JUnit 5 (current standard) JUnit 5 annotations come from the package: import org.junit.jupiter.api.*;…
🧠 What is EXISTS? EXISTS is a logical operator in SQL that checks whether a subquery returns any rows. If the subquery returns at least one row, EXISTS evaluates to TRUE. If the subquery returns no rows, EXISTS evaluates to FALSE. It’s often used in a WHERE clause to test for the existence of…
Here’s a comprehensive guide to Docker container commands with explanations and examples. I’ll organize them by category so it’s easy to reference. 1. Running Containers CommandPurposeExampledocker run <image>Run a container from an imagedocker run nginxdocker run -d <image>Run container in detached mode (background)docker run -d nginxdocker run -it <image>Run container interactively with terminaldocker run…
Here’s a comprehensive list of Docker commands related to images, broken down by category, with explanations and examples: 1. Pulling and Searching Images CommandPurposeExampledocker pull <image>Download an image from a registry (e.g., Docker Hub)docker pull nginx:latestdocker search <image>Search for an image in Docker Hubdocker search postgres 2. Listing Images CommandPurposeExampledocker images or docker image…
A Secret in Kubernetes is an object that stores sensitive information such as passwords, tokens, SSH keys, or certificates, separate from application code. Unlike ConfigMaps, Secrets are intended for confidential data and can be handled more securely. ⚙️ Definition A Secret allows you to inject sensitive data into Pods without exposing it in container…
A ConfigMap in Kubernetes is an API object used to store non-confidential configuration data in key-value pairs, so you can separate configuration from application code. It allows you to dynamically configure your applications without rebuilding container images. ⚙️ Definition A ConfigMap provides a way to inject configuration data into Pods — such as environment…
A Kubernetes Ingress is an API object that manages external access to Services, typically HTTP and HTTPS traffic, providing routing, load balancing, SSL termination, and virtual hosting — all through a single external endpoint. Think of it as the entry point to your cluster’s web traffic. 🌐 ⚙️ Definition An Ingress exposes HTTP(S) routes…
A Service in Kubernetes is an abstraction that defines a stable network endpoint for accessing a set of Pods — even if those Pods change over time. Since Pods are ephemeral (they can be created, destroyed, or rescheduled), a Service provides a consistent way to reach them via a fixed IP address, DNS name,…