Java

A good understanding of basic Java as well as Java frameworks is essential if you want to answer Java interview questions accurately. A software framework is a reusable software platform that makes the life of developers easy by providing something commonly needed out of the box; developers can then use it or extend it. A web application framework (WAF) or web framework (WF) is a software framework. It is essential for the development of different web applications, such as web resources, web APIs, and web services. Web framework can alleviate the overhead linked to everyday activities performed during web development. Prepare for Java interview through Eduthrill and experience the thrill of challenging people around the world on Java interview Questions!

Must Know Frameworks To Ace Java Interview Questions

1. Spring MVC :Being one of the most favored among programmers, Spring has a well-developed ecosystem, offering a variety of add-ons to choose from: REST APIs or SOAP web services, security (authentication and authorization, encryption), etc. This framework appears frequently in Java interview questions for freshers.

2. Struts 2 :This Java framework is quite a find for engineers who work with building contemporary Java EE web apps. The Apache Software Foundation has equipped developers with an extensive tool for creating enterprise-ready, web-facing applications, optimizing the development process from the beginning to the final point and post-go-live maintenance. This concept is the right choice if you sweat over high-load systems such as broadcasting portals.

3. Hibernate :This mapping Java framework cracks object-relational impedance mismatch issues by substituting persisting DB accesses high-level object handling functions. With every enterprise application being one of a kind, Hibernate is equipped with a great feature suite that helps backend developers fine-tune data access layer. This is an advanced ORM framework that lets you perform the database operation on Java objects (entities). It is a persistence concept that utilizes Hibernate cache to persist the data from the Java environment to the database. A working knowledge of Hibernate can give you an edge in a Java interview.

4. JSF :Being a part of Java EE, JavaServer Faces is supported by Oracle. Rich libraries and tools (including a toolset for easy user interface creation) become a magic wand that can back you up no matter how complex the application might seem.

5. Vaadin :Using GWT for rendering the end web page, Vaadin became one of the uber popular frameworks modern developers choose when creating applications for business. Utilizing a well-known component-based approach, Vaadin takes the burden off developer’s shoulder by communicating the changes made to the browser. An extensive set of UI components, along with varied widgets and controls, allows programmers to build cool applications in no time

6. Google Web Toolkit :GWT is an another free Java framework allowing coders to create and optimize sophisticated web-based apps. The GWT Software Development Kit features core Java APIs and widgets for constructing apps compiled to JavaScript after.

7. Grails :This particular web framework is regarded as a dynamic tool enhancing engineers’ productivity due to its opinionated APIs, sensible defaults, as well as its convention-over-configuration paradigm. Seamless Java integration makes this particular framework one of the top choices for plenty of programmers worldwide. A suite of powerful features, such as Spring-powered dependency injection and varied plug-ins, offer everything needed to create modern web-based apps

A basic knowledge and clear understanding of these frameworks can aid you in cracking a Java interview.

Java Interview Questions

1. What do you understand by Aspect Oriented Programming?
Enterprise applications have some common cross-cutting concerns that is applicable for different types of Objects and application modules, such as logging, transaction management, data validation, authentication etc. In Object Oriented Programming, modularity of application is achieved by Classes whereas in AOP application modularity is achieved by Aspects and they are configured to cut across different classes methods.

2. Does Spring Bean provide thread safety?
The default scope of Spring bean is singleton, so there will be only one instance per context. That means that all the having a class level variable that any thread can update will lead to inconsistent data. Hence in default mode spring beans are not thread-safe. However we can change spring bean scope to request, prototype or session to achieve thread-safety at the cost of performance. It’s a design decision and based on the project requirements

3. What is interceptor in Struts2?
Interceptors are the backbone of Struts2 Framework. Struts2 interceptors are responsible for most of the processing done by the framework, such as passing request params to action classes, making Servlet API request, response, session available to Action classes, validation, i18n support, etc.

4. How can we integrate log4j in Struts2 application?
Struts2 provides easy integration of log4j API for logging purpose, all we need to have is log4j configuration file in the WEB-INF/classes directory.

5. What is use of Hibernate Session merge() call?
Hibernate merge can be used to update existing values, however this method create a copy from the passed entity object and return it. The returned object is part of persistent context and tracked for any changes, passed object is not tracked

6. What will happen if we don’t have no-args constructor in Entity bean?
Hibernate uses Reflection API to create instance of Entity beans, usually when you call get() or load() methods. The method Class.newInstance() is used for this and it requires no-args constructor. So if you won’t have no-args constructor in entity beans, hibernate will fail to instantiate it and you will get HibernateException.

7. What does Bootstrap.groovy do?
Bootstrap.groovy allows you to define code that is ran every time your grails application starts up

8. How do I get a hold of my Spring beans in the Grails console?
Grails console injects a ctx variable, which represents the Spring context. You can then just use ctx.getBean( ‘myServiceName’ ) to get a hold of your beans

9. What is FlexTable in GWT?
FlexTable widget represents a flexible table that creates cells on demand. It can be jagged (that is, each row can contain a different number of cells) and individual cells can be set to span multiple rows or columns.

10. What is the role of JSF converter tags?
The convertor tags convert the UI component’s data to object used in a managed bean and vice versa. For example, these tags can convert a text into date object and can validate the format of input as well.

Java interview

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