n the above article, we have kept the most asked J2EE Interview Questions with their detailed answers to leondumoulin.nle yourself for your J2EE Interview with our Top .
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It does not allow duplicate values or null values. Hibernate is an open source object-relational mapping and query service. Hibernate has a more powerful association, inheritance, polymorphism, composition, and collections. It is a beautiful approach for persisting into the database using the Java objects.
Hibernate also allows you to express queries using Java-based criteria. ORM stands for Object-Relational mapping. The objects in a Java class which is mapped into the tables of a relational database using the metadata that describes the mapping between the objects and the database. It works by transforming the data from one representation to another. If the identifier is missing this method calls save. If the identifier exists, it will call update method.
The load method may return a proxy instead of a real persistent instance get never returns a proxy.
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So whenever it is necessary for an object, this mechanism is used to get objects without creating it. An object proxy is just a way to avoid retrieving an object until you need it. Hibernate 2 does not proxy objects by default. It also allows the user to express in native SQL. A thin client is a program interface to the application that does not have any operations like the query of databases, execute complex business rules, or connect to legacy applications. These files are with the. For example, if you have: Struts help you to create an extensible development environment for your application, based on published standards and proven design patterns.
Model in many applications represents the internal state of the system as a set of one or more JavaBeans. The Controller is focused on receiving requests from the client and producing the next phase of the user interface to an appropriate View component. The primary component of the Controller in the framework is a servlet of class ActionServlet. This servlet is configured by defining a set of ActionMappings. ActionErrors object that encapsulates any validation errors that have been found.
If no errors are found, return null or an ActionErrors object with no recorded error messages. The default implementation attempts to forward to the HTTP version of this method.
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ActionForm is a Java bean that associates one or more ActionMappings. A java bean become FormBean when extend org. ActionForm object is automatically populated on the server side which data has been entered by the client from UI. ActionForm maintains the session state for a web application. In action mapping, we specify action class for particular URL ie path and different target view ie forwards on to which request response will be forwarded.
The ActionMapping represents the information that the ActionServlet knows about the mapping of a particular request to an instance of a particular Action class. The mapping is passed to the execute method of the Action class, enabling access to this information directly. Model in many applications represent the internal state of the system as a set of one or more JavaBeans. Spring is a lightweight open source framework for the development of enterprise application that resolves the complexity of enterprise application development is also providing a cohesive framework for J2EE application development which is primarily based on IOC inversion of control or DI dependency injection design pattern.
The Best J2EE Interview Questions & Answers [UPDATED]
Without new, the Factory methods are used to create objects for a class. Servlets is a server-side component that provides a powerful mechanism for developing server side programs. Servlets is a server, as well as platform-independent and Servlets, are designed for various protocols. Most commonly used HTTP protocols. Servlets use the classes in the java packages javax. All servlets must implement the Servlet interface, which defines life-cycle methods.
The Servlet Interface must be implemented by all servlets. Your email address will not be published. Hashtable is a collection Synchronozed object. It is stating that it allows null values is incorrect, Hash table neither excepts null keys nor null values. What are the main benefits of the J2EE platform? The J2EE platform provides the following:.
The J2EE platform provides a framework for developing and deploying web services on the Java platform.
J2ee Interview Questions, Answers, and Explanations: J2ee Certification Review
For more info, see HTTP: J2EE containers provide for the separation of business logic from resource and lifecycle management, which means that developers can focus on writing business logic — their value add — rather than writing enterprise infrastructure. For example, the Enterprise JavaBeans EJB container implemented by J2EE technology vendors handles distributed communication, threading, scaling, transaction management, etc.
Similarly, Java Servlets simplify web development by providing infrastructure for component, communication, and session management in a web container that is integrated with a web server.
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J2EE technology is a set of standards that many vendors can implement. The vendors are free to compete on implementations but not on standards or APIs. J2EE technology makes it easier to connect the applications and systems you already have and bring those capabilities to the web, to cell phones, and to devices. J2EE offers Java Message Service for integrating diverse applications in a loosely coupled, asynchronous way.
Yes, if the other implementations are WS-I compliant. What technologies are included in the J2EE platform? The primary technologies in the J2EE platform are: This means that in addition to platform independence and complete Web services support, J2EE 1. The J2EE Management 1. Servlets now support request listeners and enhanced filters. JSP technology has simplified the page and extension development models with the introduction of a simple expression language, tag files, and a simpler tag extension API, among other features. This makes it easier than ever for developers to build JSP-enabled pages, especially those who are familiar with scripting languages.
What is the J2EE 1. Which version of the platform should I use now — 1. However, for improved reliability, scalability, and performance, it is recommended that you deploy your applications on J2EE 1. If you want to deploy your application before , and reliability,scability, and performance are critical, you should consider using a high performance application server that supports J2EE v1.
Many application server vendors are expected to release J2EE platform v1. Can applications written for the J2EE platform v1. Backwards compatibility is a requirement of the specification. Developers familiar with J2EE technology can easily apply their skills to building applications, including Web services applications, using the Sun Java Enterprise System. You can get the source for the J2EE 1.
The Web-based administration GUI 3. Solaris specific enhancements for security and logging 5. Higher performance message queue implementation. What tools can I use to build J2EE applications? There are numerous choices of tools available for developing Java and J2EE applications. Who needs the J2EE platform? ISVs need the J2EE platform because it gives them a blueprint for providing a complete enterprise computing solution on the Java platform.
Enterprise developers need J2EE because writing distributed business applications is hard, and they need a high-productivity solution that allows them to focus only on writing their business logic and having a full range of enterprise-class services to rely on, like transactional distributed objects, message oriented middleware, and naming and directory services. No matter how many developers are on your team, all of them can use the J2EE 1. There are resources that are available for free on the Sun Solaris website that may help you resolve your issues without requiring technical support.
For example you can ask questions on the forum, search for known issues on the bug data base, review the documentation, or take a look at code samples and applications to help you at no cost. Production support is also available for a fee through Sun Service. Are there compatibility tests for the J2EE platform? This test suite tests compatibility by performing specific application functions and checking results. For example, to test the JDBC call to insert a row in a database, an EJB component makes a call to insert a row and then a call is made to check that the row was inserted.
That means the licensee has the compatibility tests and has made a commitment to compatibility. Sun continues to participate in development of Tomcat at Apache, focusing on keeping Tomcat current with new versions of the specifications coming out of the Java Community Source Process.
Tomcat source and binary code is governed by the ASF license, which freely allows deployment and redistribution. What is an EJB Platform?
The Enterprise JavaBeans or EJB platform handles functions such as transaction and state management, multithreading, resource pooling, and simple searches while you concentrate on writing business logic. The API provides a platform independent and protocol independent framework to build Java technology based email client applications.
What are the design goals of J2EE architecture? The following are the design goals of J2EE architecture: The business depends on the application without the need for customer service representatives 2 Data Connectivity: The application should be able to connect to mainframe systems and other legacy systems to ensure business functions as usual 3 Accessibility: User should be able to connect the application from anywhere and from any electronic devices 4 User Interaction: The user should be able to connect to the application from desktop, laptop, PDA, and mobile 5 Flexibility: The architecture should be created in such a way that the developer just concentrates on the business component model business logic and the rest of the services are handled by the server.
What are the roles of J2EE Architect? The following are the roles of J2EE architect: What is the difference between architecture and design? It also defines the architectural design of the component interfaces. In Design, we define the components to be created for each interface, the inputs, the outputs, algorithms, and data structures. What are the activities performed in Architectural Analysis? The following activities will be performed in Architectural Analysis: This is developed to depict the high level system functionality 2 Class Diagram: This is developed to depict the functionality as classes and methods 3 Collaboration Diagram: This is developed to depict how each class talk to each other 4 Sequence Diagram: This is developed to depict the operation sequence.
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What are the activities performed in Architectural Design? The following activities will be performed in Architectural Design: Remote Method Invocation to be used will be decided b The software and hardware requirements are defined c The performance parameter and the approach to achieve will be defined d Analyze for reusing existing components or technology e Define the business logic, security, and performance of the system. What are the activities performed in the object oriented design?
The following activities will be performed in object oriented design: Decide on how classes interact with packages 2. Create dependency diagrams 3. Create deployment diagrams 4. Decide if the components software reside in deployment folder. What are the components of multi-tier architecture? The following are the components of multi-tier architecture: The front end component is present in this tier which is used to display the presentation 2.
The back end component is present in this tier which is used to communicate with database 3. The component present in this tier is used to provide business logic for the system. What are the advantages of multi-tier client server architecture? The following are the advantages of multi-tier client server architecture: What are the responsibilities of the bean developer? The following are the responsibilities of the bean developer: What are the responsibilities of application assembler?
The following are the responsibilities of application assembler: What are the responsibilities of bean deployer?