Httpsession Serialization' title='Httpsession Serialization' />JavaJ2. EE Interview Questions Architects Diary. JavaJ2. EE Interview Questions. This page is for JavaJ2. EE job seekers and interviewers and for people interested in self assessments on JavaJ2. EE technologies. There are numerous books and articles on the market covering specific topics like Java, J2. EE, EJB, Design Patterns, ANT, Maven, CVS, Multi Threading, Servlets, JSP, emerging technologies like AOP Aspect Oriented Programming, Test Driven Development TDD, Dependency Injection Dl aka Io. C Inversion of Control etc. But from an interview perspective it is not possible to brush up on all these books where each book usually has from 3. The basic purpose of this page is to cover question and only questions  on all the core concepts and key areas, which all JavaJ2. EE developers, designers and architects should be conversant with to perform well in their current jobs and to launch a successful career by doing well at interviews. The interviewer can also use this book to make sure that they hire the right candidate depending on their requirements. What language features are available to allow shared access to data in a multi threading environmentHint Synchronized block,Synchronized method,wait, notifyWhat is the difference between synchronized method and synchronized block Hint Block on subset of data. Smaller code segment. What Java language features would you use to implement a producer one thread and a consumer another thread passing data via a stack Hint wait, notifyJava language. What Java classes are provided for date manipulationIssuu is a digital publishing platform that makes it simple to publish magazines, catalogs, newspapers, books, and more online. Easily share your publications and get. Servlet interview questions,Servlet faqs, Servlet interview questions,Servlet 2. Servlet faqs, Servlet questions,Servlet Tutorial. Hint Calendar, DateWhat is the difference between String and String. Buffer Hint mutable, efficientHow do you ensure a class is Serializable Hint Implement SerializableWhat is the difference between static and instance field of a class Hint Per class vs. Per ObjectWhat methods do you need to implement to store a class in Hashtable or Hash. Map Hint hash. Code, equals. How do you exclude a field of a class from serialization Hint transientInheritance. Risk Of Installing Or Upgrading Software On Galaxy. What is the difference between an Interface and an abstract base class Hint interface inheritance, implementation inheritance. What does overriding a method mean Hint InheritanceWhat about overloadingHint different signatureMemory. What is the Java heap, and what is the stack Hint dynamic, program thread execution. Why does garbage collection occur and when can it occur Hint To recover memory, as heap gets full. If I have a circular reference of objects, but I no longer reference any of them from any executing thread, will these cause garbage collection problems Hint noExceptions. What is the problem or benefits of catching or throwing type java. Exception Hint Hides all subsequent exceptions. What is the difference between a runtime exception and a checked exception Hint Must catch or throw checked exceptions. JSPWhat is the best practice regarding the use of scriptlets in JSP pages Why Hint AvoidHow can you avoid scriptlet code Hint custom tags, Java beansWhat do you understand by the term JSP compilationHint compiles to servlet codeServlets. What does Servlet API provide to store user data between requests Hint Http. SessionWhat is the difference between forwarding a request and redirecting Hint redirect return to browser What object do you use to forward a request Hint Request. DispatcherWhat do you need to be concerned about with storing data in a servlet instance fields Hint Multi threaded. Whats the requirement on data stored in Http. Session in a clustered distributable environment Hint SerializableIf I store an object in session, then change its state, is the state replicated to distributed Session Hint No, only on set. Attribute call. How does URL pattern for servlet work in the web. Hint ddd or What is a filter, and how does it work Hint Beforeafter request, chain. JDBCWhat form of statement would you use to include user supplied valuesHint Prepared. StatementWhy might a prepared. Statement be more efficient than a statement Hint Execution plan cache. How would you prevent an SQL injection attack in JDBCHint Preparsed. Statement What is the performance impact of testing against NULL in WHERE clause on Oracle Hint Full table scan. List advantages and disadvantages in using stored procedures Hint Pro integration with existing dbase, reduced network traffic. Con not portable, mutliple language knowledge required What is the difference between sql. Date, sql. Time, and sql. Timestamp Hint Date only, time only, date and time If you had a missing int value how do you indicate this to Prepared. Statement Hint set. Nullpos, TYPEHow can I perform multiple inserts in one database interaction Hint execute. BatchGiven this problem Program reads 1. Java class in list, then converts list to XML file using reflection. Runs out of program memory. How would you fix Hint Read one row at time, limit select, allocate more heap result set cursor How might you model object inheritance in database tables Hint Table per hierarchy, table per class, table per concrete classJNDIWhat are typical uses for the JNDI API within an enterprise application Hint Resource management, LDAP accessExplain the difference between a lookup of these java compenvejbMy. Bean and ejbMy. Bean Hint logical mapping performed for java compenv What is the difference between new Initial. Context from servlet or from an EJB Hint Different JNDI environments initialized EJB controller by ejb jar. What is an LDAP server used for in an enterprise environment Hint authentication, authorizationWhat is authentication, and authorizationHint Confirming identity, confirming access rights EJBWhat is the difference between Stateless and Stateful session beans used Hint Stateful holds per client state What is the difference between Session bean and Entity bean when used Hint Entity used for persistence With Stateless Session bean pooling, when would a container typically take a instance from the pool and when would it return it Hint for each business method What is the difference between Required, Supports, Requires. New Not. Supported, Mandatory, Never Hint Needs transaction, existing OK but doesnt need, must start new one, suspends transaction, must already be started, error if transactionWhat is pass by reference and pass by value, and how does it affect J2. EE applications Hint Reference to actual object versus copy of object. RMI pass by value. What EJB patterns, best practices are you aware of Describe at least two Hint Faade, delegate, value list, DAO, value object. Describe some issuesconcerns you have with the J2. EE specification Hint Get their general opinion of J2. EEWhat do you understand by the term offline optimistic locking or long lived business transaction How might you implement this using EJB Hint version number, date, field comparisons. Explain performance difference between getting a list of summary information e. BMP entity vs. Session using DAO Hint BMP n1 database reads, n RMI calls. What is meant by a coarse grained and a fine grained interfaceHint Amount of data transferred per method callXMLXSLTWhat is the difference between a DOM parser and a SAX parser Hint DOM reads entire model, SAX event published during parsing.