Java Code Gists

Jenkins CI/CD for Github using Deploy Keys

January 15, 2023 by T Tak

When setting up a continuous integration and deployment (CI/CD) pipeline using Jenkins and GitHub deploy keys, 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 GitHub deploy keys: Set up a Jenkins server: This can be done … Read more

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

January 13, 2023 by T Tak

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

January 11, 2023 by T Tak

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

Parameter 0 of constructor in org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration required a bean of type ‘javax.sql.DataSource’ that could not be found. – Bean method ‘dataSource’ not loaded because @ConditionalOnProperty (spring.datasource.jndi-name) did not find property ‘jndi-name’ – Bean method ‘dataSource’ not loaded because @ConditionalOnBean (types: org.springframework.boot.jta.XADataSourceWrapper; SearchStrategy: all) did not find any beans

January 11, 2023 by TAK

This error message is indicating that your application is unable to find a bean of type ‘javax.sql.DataSource’ that is required by HibernateJpaAutoConfiguration. The error message suggests that there is a missing @ConditionalOnProperty annotation on the dataSource() method, which is causing the bean not to be loaded. The @ConditionalOnProperty annotation checks for the presence of a … Read more

Jenkins CI/CD using Github Account

January 11, 2023 by T Tak

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

January 8, 2023 by T Tak

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

import java.util.HashMap;
import java.util.Map;

public class AgeGenderStatistics {
  public static void main(String[] args) {
    // Create a map to store the age and gender of each person
    Map&lt;Integer, String&gt; persons = new HashMap&lt;&gt;();
    persons.put(34, "Male");
    persons.put(20, "Female");
    persons.put(40, "Male");
    persons.put(25, "Female");
    persons.put(30, "Male");

    // Initialize the age and gender counters
    int maleCount = 0;
    int femaleCount = 0;
    int totalAge = 0;

    // Iterate through the map and update the counters
    for (Map.Entry&lt;Integer, String&gt; entry : persons.entrySet()) {
      int age = entry.getKey();
      String gender = entry.getValue();

      if (gender.equals("Male")) {
        maleCount++;
      } else if (gender.equals("Female")) {
        femaleCount++;
      }

      totalAge += age;
    }

    // Calculate the average age of the group
    double averageAge = (double) totalAge / persons.size();

    // Print the age and gender statistics
    System.out.println("Number of males: " + maleCount);
    System.out.println("Number of females: " + femaleCount);
    System.out.println("Average age: " + averageAge);
  }
}

import java.util.HashMap;

import java.util.Map;

public class AgeGenderStatistics {

public static void main(String[] args) {

// Create a map to store the age and gender of each person

Map<Integer, String> persons = new HashMap<>();

persons.put(34, "Male");

persons.put(20, "Female");

persons.put(40, "Male");

persons.put(25, "Female");

persons.put(30, "Male");

// Initialize the age and gender counters

int maleCount = 0;

int femaleCount = 0;

int totalAge = 0;

// Iterate through the map and update the counters

for (Map.Entry<Integer, String> entry : persons.entrySet()) {

int age = entry.getKey();

String gender = entry.getValue();

if (gender.equals("Male")) {

maleCount++;

} else if (gender.equals("Female")) {

femaleCount++;

}

totalAge += age;

}

// Calculate the average age of the group

double averageAge = (double) totalAge / persons.size();

// Print the age and gender statistics

System.out.println("Number of males: " + maleCount);

System.out.println("Number of females: " + femaleCount);

System.out.println("Average age: " + averageAge);

}

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

January 8, 2023 by T Tak

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

January 10, 2023January 1, 2023 by T Tak

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

June 16, 2021June 16, 2021 by T Tak

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()’

June 16, 2021May 11, 2021 by T Tak

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.