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Object Oriented Programming Articles
Page 422 of 589
Difference between DispatcherServlet and ContextLoaderListener in Spring
ContextLoaderListener creates a root web-application-context for the web-application and puts it in the ServletContext. This context can be used to load and unload the spring-managed beans ir-respective of what technology is being used in the controller layer(Struts or Spring MVC).DispatcherServlet creates its own WebApplicationContext and the handlers/controllers/view-resolvers are managed by this context.Sr. No.KeyDispatcherServletContextLoaderListener1BasicThe task of the DispatcherServlet is to send request to the specific Spring MVC controller ContextLoaderListener reads the Spring configuration file (with value given against contextConfigLocation in web.xml ), parses it and loads the singleton bean defined in that config file. So we initialize the web application with ContextLoaderListener ...
Read MoreDifference between @Inject and @Autowired
@Inject and @Autowired both annotations are used for autowiring in your application.@Inject annotation is part of Java CDI which was introduced in Java 6, whereas @Autowire annotation is part of spring framework. Both annotations fulfill same purpose therefore, anything of these we can use in our application.Sr. No.Key@Inject@Autowired1BasicIt is part of Java CDIIt is part of Spring framework2RequiredIt has no required attributeIt has required attribute3Default ScopeDefault scope of the autowired beans is SingletonDefault scope of the inject beans is prototype4AmbiguityIn case of ambiguity in beans for injection then @Named qualifier should be added in your code.In case of ambiguity in ...
Read MoreDifference between singleton and prototype bean scope.
Spring framework supports five types of bean scope −SingletonPrototypeRequestSessionGlobal SessionAs per the spring documentation −Singleton − It returns a single bean instance per Spring IoC container. This single instance is stored in a cache of such singleton beans, and all subsequent requests and references for that named bean return the cached object.Spring singleton is different than Java singleton. In java, one instance of the bean is created per JVM whereas in spring, one instance of the bean is created per application context.Proptype −As per the spring documentation −Spring does not manage the complete lifecycle of a prototype bean: the container ...
Read MoreDifference between @Bean and @Component annotation in Spring.
Spring supports multiple types annotations such as @Component, @Controller, @service @Repository and @Bean. All theses can be found under the org.springframework.stereotype package.When classes in our application are annotated with any of the above mentioned annotation then during project startup spring scan(using @componentScan) each class and inject the instance of the classes to the IOC container. Another thing the @ComponentScan would do is running the methods with @Bean on it and restore the return object to the Ioc Container as a bean.Sr. No.Key@Bean@Component1Auto detectionIt is used to explicitly declare a single bean, rather than letting Spring do it automatically. If any class ...
Read MoreDifference between Dependency Injection and Factory Pattern.
Factory and Dependency injection both are the design pattern which can be used to enhance loose coupling abilities between the software components. Factory design pattern is used to create objects. But, injection and life cycle management of the object should be handled by programmer within the application. There is no way to configure everything in a single place. Therefore, programmers need to call object creation logic wherever it needed which eventually hinder the loose coupling abilities.In DI design pattern, creation of object, injecting of the instance and life cycle management of the instance can be handled outside the code. In spring, ...
Read MoreDifference between IOC and Dependency Injection in Spring.
Inversion of control is a design principle which helps to invert the control of object creation.According to the paper written by Martin Fowler , inversion of control is the principle where the control flow of a program is inverted: instead of the programmer controlling the flow of a program, the external sources (framework, services, other components) take control of it. It's like we plug something into something else. He mentioned an example about EJB 2.0.Dependency Injection is a design pattern which implements IOC principle. DI provides objects that an object needs. Let’s say, class X is dependent on Y. So ...
Read MoreDifference Between Constructor Injection and Setter Injection in Spring
Dependency Injection is a practice to pass dependent object to other objects. Spring has two types of Dependency Injection :Constructor based Injection -When container call the constructor of the class. It should be used for mandatory dependencies.Let’s say Class X is tightly dependent on Class Y then we should use constructor based injection. Setter based Injection - It can be used by calling setter methods on your beans. It should be used for optional dependencies.Both types of injection has their own pros and cons. Below is a list of some differences −Sr. No.KeyConstructor based InjectionSetter based Injection1CircularIt doesn’t allow to ...
Read MoreFind the last element of a list in scala
Suppose we have a list in Scala, this list is defined under scala.collection.immutable package. As we know, a list is a collection of same type elements which contains immutable (cannot be changed) data. We generally apply last function to show last element of a list.Using last keywordThe following Scala code is showing how to print the last element stored in a list of Scala.Example import scala.collection.immutable._ object HelloWorld { def main(args: Array[String]) { val temp_list: List[String] = List("Hello", "World", "SCALA", "is", "awesome") println("Elements of temp_list: " + temp_list.last) } }Output$scala HelloWorld Elements of ...
Read MoreHow to implement LongToIntFunction using lambda and method reference in Java?
LongToIntFunction is a functional interface from java.util.function package introduced in Java 8. This functional interface accepts a long-valued parameter as input and produces an int-valued result. LongToIntFunction interface can be used as an assignment target for a lambda expression or method reference. This interface contains only one abstract method: applyAsInt() and doesn't contain any default and abstract methods.Syntax@FunctionalInterface interface LongToIntFunction { int applyAsInt(long value); }Example of Lambda Expressionimport java.util.function.LongToIntFunction; public class LongToIntLambdaTest { public static void main(String args[]) { LongToIntFunction getInt = longVal -> { ...
Read MoreHow to implement LongToDoubleFunction using lambda and method reference in Java?
LongToDoubleFunction is a built-in functional interface and part of java.util.function package. This functional interface accepts a long-valued parameter as input and produces a double-valued result. LongToDoubleFunction can be used as an assignment target for a lambda expression or method reference. It contains only one abstract method: applyAsDouble().Syntax@FunctionalInterface interface LongToDoubleFunction { double applyAsDouble(long value); }Example of Lambda Exampleimport java.util.function.LongToDoubleFunction; public class LongToDoubleLambdaTest { public static void main(String args[]) { LongToDoubleFunction getDouble = longVal -> { // lambda expression double doubleVal = longVal; ...
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