Problem: 03-May-2021 19:15:28.056 SEVERE [ajp-nio-9209-exec-4] org.apache.catalina.core.StandardContext.listenerStart Error configuring application listener of class []java.lang.ClassNotFoundException: Cause : jaxws-rt.jar is either missing or has multiple versions. Solution 1:   If you don’t have this jar add it to tomcat/lib folder.  Solution 2:    For maven, you can add the dependency in your pom.xml. Make sure to pick … [Read more…]

How to schedule tasks with Spring boot

Overview Task scheduling refers to executing a task on a particular time frame or repeating the task by running a process in a fixed interval. Spring boot provides @Scheduled and @EnableScheduling annotations for configuring and scheduling tasks, periodically. Spring allows us to configure the parameters of the @Scheduled annotation by scheduling a task on a … [Read more…]

Spring Security Interview Questions

Below is a list of questions asked frequently during technical interviews on the topic of Spring security. For details and usage of spring security concepts in real-world examples, please check-out these posts: Secure a REST Service Basic HTTP Authentication What is Spring Security? Spring security is a customizable framework to provide authentication (establishing that user/device … [Read more…]


1.    What is Spring Boot? To start a new Spring project one has to add the maven dependencies or the build path, add configurations, configure the application server, etc. Therefore, it requires some efforts from the developer before actually starting the project from scratch. Here, Spring Boot comes into action and provides automation for these … [Read more…]

Convert Array to Streams in Java 8

A new abstract layer was introduced in Java 8 called ‘Stream’.   With the help you Stream, data can be processed in a declarative way which is quite comparable to SQL statements. Stream basically represents a chain of objects from a particular source that supports aggregate operations. The characteristics of Stream are mentioned below: Sequence of … [Read more…]

JShell – Java 9 REPL

Introduction Java is soon to release its new version – Java 9 with lots of exciting new features which will make our programming more easy and fast. The new Java release is everything about Project Jigsaw whose aim is to make the Java SE Platform and JDK more scalable for small computing devices. It will … [Read more…]

Java Collections interview questions and answers

Here is the list of Java Collections interview questions. These questions have been asked over time and are still being asked in interviews. It is good to go through them to understand the various concepts in Collections. Java Collections Interview Questions and Answers What is a HashSet and how does it work internally in Java? … [Read more…]