Amazon Keyspaces – its usage, limitations and differences with Apache Cassandra

Amazon Keyspaces is a fully managed database service offered by Amazon Web Services (AWS). It is based on Apache Cassandra, and it is designed to be scalable, highly available, and easy to use.Amazon Keyspaces allows you to store, retrieve, and manage large amounts of data in a distributed database. It is well-suited for applications that … Read more

Connect to Apache Cassandra using Java

To connect to Cassandra in Java, you will need to include the Cassandra driver in your project. Here is an example of how you can do this: Download the Cassandra Java driver from the Apache Cassandra website or from Maven Central. Add the driver to your project. If you are using Maven, you can include … Read more

Jenkins CI/CD using Github Account

When setting up a continuous integration and deployment (CI/CD) pipeline using Jenkins and a GitHub account, you can use the Jenkins GitHub plugin to interact with the GitHub repository. Here are the general steps for setting up a basic Jenkins CI/CD pipeline using a GitHub account: Set up a Jenkins server: This can be done … Read more

Write a Java program to generate age gender statistics

Here is a very simple Java program that generates age and gender statistics for a group of persons:

This program defines a map called persons, which stores the age and gender of each person as a key-value pair. The program then iterates through the map, updating counters for the number of males and females, … Read more

Hello World in Java

Here is how you can write “Hello, World!” in Java: public class HelloWorldJava { public static void main(String[] args) { System.out.println(“Hello, World!”); } } To run this program, you will need to save it in a file called “HelloWorldJava.java”, and then use a Java compiler to compile it. Once the program has been compiled, you … Read more

Jenkins CI/CD with Github with Webhooks

Creating a CI/CD pipeline using Jenkins and GitHub can be a bit involved, but I can give you an overview of the process. First, you’ll need to set up a Jenkins server. This can be done by installing Jenkins on a server or by using a cloud-based version, such as Jenkins on Azure or AWS. … Read more

java.lang.IllegalArgumentException: Child name [/mytestapp] is not unique

Sometimes while deploying war to tomcat leads to the error. 15-Jun-2021 13:41:40.282 INFO [ajp-nio-127.0.0.1-8209-exec-10] org.apache.catalina.startup.HostConfig.undeploy Undeploying context [/mytestapp] 15-Jun-2021 13:41:40.956 INFO [ajp-nio-127.0.0.1-8209-exec-10] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [/opt/tomcat/webapps/mytestapp.war] 15-Jun-2021 13:41:40.963 INFO [Catalina-utility-1] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [/opt/tomcat/webapps/mytestapp.war] 15-Jun-2021 13:41:40.964 SEVERE [Catalina-utility-1] org.apache.catalina.startup.HostConfig.deployWAR Error deploying web application archive [/opt/tomcat/webapps/mytestapp.war] java.lang.IllegalArgumentException: Child name [/mytestapp] is not … Read more

java.lang.NoSuchMethodError: ‘org.junit.jupiter.api.extension.TestInstances org.junit.jupiter.api.extension.ExtensionContext.getRequiredTestInstances()’

Problem: java.lang.NoSuchMethodError: ‘org.junit.jupiter.api.extension.TestInstances org.junit.jupiter.api.extension.ExtensionContext.getRequiredTestInstances()’ Using : openJdk16 maven3 eclipse2021-03   Solution: I was using maven dependency for Junit 5 <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <version>5.3.0</version> <scope>test</scope> </dependency> And to solve this issue I had to update the dependency to <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <version>5.5.0</version> <scope>test</scope> </dependency>   After that change eclipse did run the tests fine.

Spring Boot Exception Handling

We have seen how spring boot helps us quickly put together RESTful web-services and web applications. When an application or service works as intended it leads to happy users and productivity. However, there are times when software may not be able to fulfill its functions – due to errors or exceptions. The causes of errors … Read more

Introduction to GraphQL with Spring Boot

This article is an introduction to GraphQL with spring boot. We will discuss basic concepts of GraphQL and setup a spring boot app for schema-driven development. What is GraphQL ? GraphQL is a data query language. It was created by Facebook. GraphQL provides a new API standard similar to REST. In REST API, the fundamental … Read more