Spring Core

In this post, we will see about an exception: No qualifying bean of type. Exceptions are least expected but you might get it while working with Spring. or Spring boot. Did you get this exception: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type? If yes, let’s see different reasons for it. Reason 1: You forgot to declare […]

In this post, we will see how to create Spring hello world XML based configuration example. Here are simple steps to create Spring XML configuration example. 1. Create a simple java maven project. 2. Maven dependency put spring and cglib maven dependency in pom.xml. [crayon-67266f83e9a4f737302662/] So your pom.xml will look like: [crayon-67266f83e9a56880332798/] 3. Create Bean class […]

In this post, we will see how to inject prototype bean scope into Singleton Instance in Spring. This is one of the most asked Spring interview questions. Problem When you inject prototype bean to singleton bean, prototype bean still behave like a singleton bean. Let’s understand this with the help of example. 1. Create a […]

In this post, we will discuss one of the most asked Spring interview questions. What happens if there are circular dependencies in Spring. Problem What if there are circular dependencies in Spring? For example: Class A requires an instance of Class B and Class B requires an instance of Class A. Let’s create an example […]

In this post, we will see about Spring init-method and destroy-method. When bean is instantiated or destroyed , there are some operations you may need to perform, so you can use init-method and destroy-method to call this methods while bean is being created or destroyed. Lets understand it with the help of simple example: For […]

When you are working on spring or spring mvc application, you may encounter below error message. org.xml.sax.SAXParseException: The prefix “context” for element “context:component-scan” is not bound . or org.xml.sax.SAXParseException: The prefix “context” for element “context:annotation-config” is not bound . This issue generally occurs when you do not include context namespace. For example: Lets say you have below […]

In this post , we will see how to load multiple spring bean configuration files. Sometimes, you have multiple spring bean configuration file , you may have different configuration file for service, different for business object. When you are working on complex application, it is not good practice to have only single xml configuration, you […]

Spring autowiring by constructor is similar to autowiring by type but it is applied to constructor argument. If more than one bean property matches, then it throws fatal exception. Below digram will make it clear: For example: I am taking example of autowire by “constructor” here.It will be almost same as Dependency injection via setter method with […]

Spring autowiring byType means autowiring on the basis of datatype. if any bean property datatype matches with exact one other bean’s datatype declaration then spring will automatically takes care of dependency. If more than one bean property matches, then it throws fatal exception. Below diagram will make it clear: For example: I am taking example […]