Java/J2ee Interview Questions

Hi Friends this Post is about Java interview questions and Core Java Interview questions .  As you know now a days cracking job interviews are very tough and we have to learn lot of technologies to crack the interviews . Expectations of companies are growing as they want multiple skilled person who has knowledge in Java , Core Java , J2EE and Many More.
Java /Core Java is a Vast technology as it have loads of things in it . Its very hard for a person  to learn all the competencies  i am trying to summarize and Bring all the Java \Core Java Interview questions on one Platform . Its my try to help you folks for free and Help you crack Job interviews

Everyone who is in IT knows that we wont  work on All the part of any technologies we will be working on a particular part but when we go for a Job Interview we have to Prepare all the supporting technologies too so we have to prepared for the same .

Some Tips which may Help you to crack the Job Interviews

1) Prepare you Cv\Resume Very well  now what that means  ...It means that what you have written in you Resume you should be well confident  on that , Dont include that topics in your CV which you have very little knowledge  It may have adverse effect if the Interviewer starts asking questions from that Topics.

2) First Questions in 99% Cases will be Brief Me about yourself or Tell me about yourself . You should Very well prepared for that Prepare  it will short description of 3 5 Minutes ,Try to highlight your Strength , Tell your Roles and Responsibilities in Your Current Project . Explain what you work and how you work .
3) Don't Try to Bluff Interviewers or Make them Fool , Try to Answers the question what has been asked.

4) Tell no if you don't know the answers try to be truth as much as possible if Some questions is asked you have little knowledge then please tell the same .
All the best Folks for your Job Hunting. Please free to ask any questions in Comments.

Java Interview questions

Hi Friends Java Interview questions has been designed for you to use to the Java Programming Interview questions and answers.

Java is Robust programming language , its intended is to 'write once and run anywhere'

Java is object oriented programming language . 90 % of the application are build  in Java as per recent surveys.

Most of the applications are run on java  and or they need java support to be executed . 

Java has been vastly in demand in all the MNC's . If you are an expert of Java you will never have to sit back empty handed you can easily get jobs . 

Java  have several stages  we have basic Java which is called core java , we have J2ee , we have Struts , Spring , Java beans and many more . Its a ocean  which have many things beneath itself .

Java Interview questions will provide you a very good overview whats is asked in your java interview in companies.

Thanks and all the best for your job interview.

1. What is a transient variable?

A transient variable is a variable that may not be serialized.

2. Which containers use a border Layout as their default layout?

The Window, Frame and Dialog classes use a border layout as their default layout.

Best J2ME Interview Questions And Answers

J2ME Interview Questions And Answers
What is J2ME ?
Java 2, Micro Edition is a group of specifications and technologies that pertain to Java on small devices. The J2ME moniker covers a wide range of devices, from pagers and mobile telephones through set-top boxes and car navigation systems. The J2ME world is divided into configurations and profiles, specifications that describe a Java environment for a specific class of device.
What is J2ME WTK ?
The J2ME Wireless Toolkit is a set of tools that provides developers with an emulation environment, documentation and examples for developing Java applications for small devices. The J2ME WTK is based on the Connected Limited Device Configuration (CLDC) and Mobile Information Device Profile (MIDP) reference implementations, and can be tightly integrated with Forte for Java

Best J2SE Interview Questions And Answers

What is abstract ?
A Java keyword used in a class definition to specify that a class is not to be instantiated, but rather inherited by other classes. An abstract class can have abstract methods that are not implemented in the abstract class, but in subclasses.
What is abstract class ?
A class that contains one or more abstract methods, and therefore can never be instantiated. Abstract classes are defined so that other classes can extend them and make them concrete by implementing the abstract methods.
What is abstract method ?
A method that has no implementation.
What is Abstract Window Toolkit (AWT) ?
A collection of graphical user interface (GUI) components that were implemented using native-platform versions of the components. These components provide that subset of functionality which is common to all native platforms. Largely supplanted by the Project Swing component set. See also Swing.
What is access control ?
The methods by which interactions with resources are limited to collections of users or programs for the purpose of enforcing integrity, confidentiality, or availability constraints.
What is ACID ?
The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.
What is actual parameter list ?
The arguments specified in a particular method call. See also formal parameter list.
What is API ?
Application Programming Interface. The specification of how a programmer writing an application accesses the behavior and state of classes and objects.
What is applet ?
A component that typically executes in a Web browser, but can execute in a variety of other applications or devices that support the applet programming model.
What is ASCII ?
American Standard Code for Information Interchange. A standard assignment of 7-bit numeric codes to characters. See also Unicode.
What is atomic ?
Refers to an operation that is never interrupted or left in an incomplete state under any circumstance.
What is authentication ?
The process by which an entity proves to another entity that it is acting on behalf of a specific identity.
What is autoboxing ?
Automatic conversion between reference and primitive types.
What is bean ?
A reusable software component that conforms to certain design and naming conventions. The conventions enable beans to be easily combined to create an application using tools that understand the conventions.
What is binary operator ?
An operator that has two arguments.
What is bitwise operator ?
An operator that manipulates the bits of one or more of its operands individually and in parallel. Examples include the binary logical operators (&, |, ^), the binary shift operators (<< , >>, >>> ) and the unary one's complement operator (~).
What is block ?
In the Java programming language, any code between matching braces. Example: { x = 1; }.
Application Programming Interface. The specification of how a programmer writing an application accesses the behavior and state of classes and objects.
What is applet ?
A component that typically executes in a Web browser, but can execute in a variety of other applications or devices that support the applet programming model.
What is ASCII ?
American Standard Code for Information Interchange. A standard assignment of 7-bit numeric codes to characters. See also Unicode.
What is atomic ?
Refers to an operation that is never interrupted or left in an incomplete state under any circumstance.
What is authentication ?
The process by which an entity proves to another entity that it is acting on behalf of a specific identity.
What is autoboxing ?
Automatic conversion between reference and primitive types.
What is bean ?
A reusable software component that conforms to certain design and naming conventions. The conventions enable beans to be easily combined to create an application using tools that understand the conventions.
What is binary operator ?
An operator that has two arguments.
What is bitwise operator ?
An operator that manipulates the bits of one or more of its operands individually and in parallel. Examples include the binary logical operators (&, |, ^), the binary shift operators (<< , >>, >>> ) and the unary one's complement operator (~).
What is block ?
In the Java programming language, any code between matching braces. Example: { x = 1; }.
The process of transferring an enterprise bean from secondary storage to memory. (See passivation.)
What is "anonymous access" ?
Accessing a resource without authentication.
What is class ?
In the Java programming language, a type that defines the implementation of a particular kind of object. A class definition defines instance and class variables and methods, as well as specifying the interfaces the class implements and the immediate superclass of the class. If the superclass is not explicitly specified, the superclass will implicitly be Object.
What is class method ?
A method that is invoked without reference to a particular object. Class methods affect the class as a whole, not a particular instance of the class. Also called a static method. See also instance method.
What is class variable ?
A data item associated with a particular class as a whole--not with particular instances of the class. Class variables are defined in class definitions. Also called a static field. See also instance variable.
What is classpath ?
An environmental variable which tells the Java virtual machine1 and Java technology-based applications where to find the class libraries, including user-defined class libraries.
What is client ?
In the client/server model of communications, the client is a process that remotely accesses resources of a compute server, such as compute power and large memory capacity.
What is CODEBASE ?
Works together with the code attribute in the <APPLET> tag to give a complete specification of where to find the main applet class file: code specifies the name of the file, and codebase specifies the URL of the directory containing the file.
What is comment ?
In a program, explanatory text that is ignored by the compiler. In programs written in the Java programming language, comments are delimited using // or /*...*/.
What is commit ?
The point in a transaction when all updates to any resources involved in the transaction are made permanent.
What is compilation unit ?
The smallest unit of source code that can be compiled. In the current implementation of the Java platform, the compilation unit is a file.
What is compiler ?
A program to translate source code into code to be executed by a computer. The Java compiler translates source code written in the Java programming language into bytecode for the Java virtual machine1. See also interpreter.
What is compositing ?
The process of superimposing one image on another to create a single image.
What is constructor ?
A pseudo-method that creates an object. In the Java programming language, constructors are instance methods with the same name as their class. Constructors are invoked using the new keyword.

What is const ?
A reserved Java keyword not used by current versions of the Java programming language.

What is continue ?
A Java keyword used to resume program execution at the end of the current loop. If followed by a label, continue resumes execution where the label occurs.
What is conversational state ?
The field values of a session bean plus the transitive closure of the objects reachable from the bean's fields. The transitive closure of a bean is defined in terms of the serialization protocol for the Java programming language, that is, the fields that would be stored by serializing the bean instance.
What is CORBA ?
Common Object Request Broker Architecture. A language independent, distributed object model specified by the Object Management Group (OMG).
What is core class ?
A public class (or interface) that is a standard member of the Java Platform. The intent is that the core classes for the Java platform, at minimum, are available on all operating systems where the Java platform runs. A program written entirely in the Java programming language relies only on core classes, meaning it can run anywhere. .
What is core packages ?
The required set of APIs in a Java platform edition which must be supported in any and all compatible implementations.
What is credentials ?
The information describing the security attributes of a principal. Credentials can be acquired only through authentication or delegation.
What is critical section ?
A segment of code in which a thread uses resources (such as certain instance variables) that can be used by other threads, but that must not be used by them at the same time.
What is declaration ?
A statement that establishes an identifier and associates attributes with it, without necessarily reserving its storage (for data) or providing the implementation (for methods). See also definition.
What is default ?
A Java keyword optionally used after all case conditions in a switch statement. If all case conditions are not matched by the value of the switch variable, the default keyword will be executed.
What is definition ?
A declaration that reserves storage (for data) or provides implementation (for methods). See also declaration.
What is delegation ?
An act whereby one principal authorizes another principal to use its identity or privileges with some restrictions.

What is deprecation ?
Refers to a class, interface, constructor, method or field that is no longer recommended, and may cease to exist in a future version.

What is derived from ?
Class X is "derived from" class Y if class X extends class Y. See also subclass, superclass.
What is distributed ?
Running in more than one address space.
What is distributed application ?
An application made up of distinct components running in separate runtime environments, usually on different platforms connected through a network. Typical distributed applications are two-tier (client/server), three-tier (client/middleware/server), and n-tier (client/multiple middleware/multiple servers).
What is do ?
A Java keyword used to declare a loop that will iterate a block of statements. The loop's exit condition can be specified with the while keyword.
What is DOM ?
Document Object Model. A tree of objects with interfaces for traversing the tree and writing an XML version of it, as defined by the W3C specification.
What is double ?
A Java keyword used to define a variable of type double.
What is double precision ?
In the Java programming language specification, describes a floating point number that holds 64 bits of data. See also single precision.
What is DTD ?
Document Type Definition. A description of the structure and properties of a class of XML files.
What is else ?
A Java keyword used to execute a block of statements in the case that the test condition with the if keyword evaluates to false.
What is Embedded Java Technology ?
The availability of Java 2 Platform, Micro Edition technology under a restrictive license agreement that allows a licensee to leverage certain Java technologies to create and deploy a closed-box application that exposes no APIs.
What is encapsulation ?
The localization of knowledge within a module. Because objects encapsulate data and implementation, the user of an object can view the object as a black box that provides services. Instance variables and methods can be added, deleted, or changed, but as long as the services provided by the object remain the same, code that uses the object can continue to use it without being rewritten. See also instance variable, instance method.
What is enum ?
A Java keyword used to declare an enumerated type.
What is enumerated type ?
A type whose legal values consist of a fixed set of constants.
What is Java IDL ?
Java Interface Definition Language
What is Java Interface Definition Language (IDL) ?
A set of Java APIs that provide CORBA (Common Object Request Broker Architecture) interoperability and connectivity capabilities for the J2EE platform. These capabilities enable J2EE applications to invoke operations on remote network services using the OMG IDL and IIOP.
What is Java Media APIs ?
A set of APIs that support the integration of audio and video clips, 2D fonts, graphics, and images as well as 3D models and telephony.
What is Java Media Framework ?
The core framework supports clocks for synchronizing between different media (e.g., audio and video output). The standard extension framework allows users to do full audio and video streaming.
What is Java Naming and Directory Interface (JNDI) ?
A set of APIs that assists with the interfacing to multiple naming and directory services.
What is Java Native Interface ?
A standard programming interface for writing Java native methods and embedding the JVM into native applications. The primary goal is binary compatibility of native method libraries across all JVM implementations on a given platform.
What is Java Platform ?
Consists of class libraries, a Java virtual machine (JVM) and class loader (which comprise the runtime environment) and a compiler, debugger and other tools (which comprise the development kit). In addition, the runtime platform is subject to a set of compatibility requirements to ensure consistent and compatible implementations. Implementations that meet the compatibility requirements may qualify for Sun's targeted compatibility brands. Java 2 is the current generation of the Java Platform.
What is Java Platform Editions ?
A Java platform "edition" is a definitive and agreed-upon version of the Java platform that provides the functionality needed over a broad market segment. An edition is comprised of two kinds of API sets: (i) "core packages," which are essential to all implementations of a given platform edition, and (ii) "optional packages," which are available for a given platform edition and which may be supported in a compatible implementation.

There are 3 distinct editions of the Java Platform:

* Java 2 Platform, Enterprise Edition:
The edition of the Java platform that is targeted at enterprises to enable development, deployment, and management of multi-tier server-centric applications.
* Java 2 Platform, Micro Edition:
The edition of the Java platform that is targeted at small, standalone or connectable consumer and embedded devices to enable development, deployment, and management of applications that can scale from smart cards through mobile devices and set-top boxes to conventional computing devices.
* Java 2 Platform, Standard Edition:
The edition of the Java platform that enables development, deployment, and management of cross-platform, general-purpose applications.
What is Java Remote Method Invocation (RMI) ?
A distributed object model for Java program to Java program, in which the methods of remote objects written in the Java programming language can be invoked from other Java virtual machines1, possibly on different hosts.
What is Java Runtime Environment (JRE) ?
A subset of the Java Development Kit (JDK) for end-users and developers who want to redistribute the runtime environment alone. The Java runtime environment consists of the Java virtual machine1, the Java core classes, and supporting files.
What is Java virtual machine ?
A software "execution engine" that safely and compatibly executes the byte codes in Java class files on a microprocessor (whether in a computer or in another electronic device).
What is JavaBeans ?
A portable, platform-independent reusable component model. A component that conforms to this model is called a bean.
What is JavaCheck ?
A tool for checking compliance of applications and applets to a specification.
What is JavaSafe ?
A tool for tracking and managing source file changes, written in Java.
What is JavaScript ?
A Web scripting language that is used in both browsers and Web servers. Like all scripting languages, it is used primarily to tie other components together or to accept user input.
What is JavaSpaces ?
A technology that provides distributed persistence and data exchange mechanisms for code in Java.
What is JDBC ?
Java Database Connectivity.
What is JDK ?
Java Development Kit. A software development environment for writing applets and application in Java .
What is JFC ?
Java Foundation Classes.
What is Jini Technology ?
A set of Java APIs that may be incorporated an optional package for any Java 2 Platform Edition. The Jini APIs enable transparent networking of devices and services and eliminates the need for system or network administration intervention by a user. The Jini technology is currently an optional package available on all Java platform editions.
What is JNDI ?
Java Naming and Directory Interface.
What is JNI ?
Java Native Interface.
What is JRE ?
Java Runtime Environment
What is Just-in-time (JIT) Compiler ?
A compiler that converts all of the bytecode into native machine code just as a Java program is run. This results in run-time speed improvements over code that is interpreted by a Java virtual machine.
What is JVM ?
Java Virtual Machine (JVM).
What is keyword ?
Java sets aside words as keywords - these words are reserved by the language itself and therefore are not available as names for variables or methods.
What is lexical ?
Pertaining to how the characters in source code are translated into tokens that the compiler can understand.
What is linker ?
A module that builds an executable, complete program from component machine code modules. The Java linker creates a runnable program from compiled classes. See also compiler, interpreter, runtime system.
What is literal ?
The basic representation of any integer, floating point, or character value. For example, 3.0 is a double-precision floating point literal, and "a" is a character literal.
What is local variable ?
A data item known within a block, but inaccessible to code outside the block. For example, any variable defined within a method is a local variable and can't be used outside the method.
What is long ?
A Java keyword used to define a variable of type long.
What is member ?
A field or method of a class. Unless specified otherwise, a member is not static.
What is method ?
A function defined in a class. See also instance method, class method. Unless specified otherwise, a method is not static.
What is multithreaded ?
Describes a program that is designed to have parts of its code execute concurrently. See also thread.
What is native ?
A Java keyword that is used in method declarations to specify that the method is not implemented in the same Java source file, but rather in another language.
What is new ?
A Java keyword used to create an instance of a class.
What is null ?
The null type has one value, the null reference, represented by the literal null, which is formed from ASCII characters. A null literal is always of the null type.
What is object ?
The principal building blocks of object-oriented programs. Each object is a programming unit consisting of data (instance variables) and functionality (instance methods). See also class.
What is object-oriented design ?
A software design method that models the characteristics of abstract or real objects using classes and objects.
What is octal What is object-oriented design ?
The numbering system using 8 as its base, using the numerals 0-7 as its digits. In programs written in the Java programming language, octal numbers must be preceded with 0. See also hexadecimal.
What is optional packages ?
The set or sets of APIs in a Java platform edition which are available with and may be supported in a compatible implementation. Over time, optional packages may become required in an edition as the marketplace requires them.
What is ORB ?
Object Request Broker. A library than enables CORBA objects to locate and communicate with one another.
What is OS principal ?
A principal native to the operating system on which the Java platform is executing.
What is OTS ?
Object Transaction Service. A definition of the interfaces that permit CORBA objects to participate in transactions.
What is overloading ?
Using one identifier to refer to multiple items in the same scope. In the Java programming language, you can overload methods but not variables or operators.
What is overriding ?
Providing a different implementation of a method in a subclass of the class that originally defined the method.
What is package ?
A group of types. Packages are declared with the package keyword.
What is peer ?
In networking, any functional unit in the same layer as another entity.
What is persistence ?
The protocol for transferring the state of a bean between its instance variables and an underlying database.
What is pixel ?
The picture element on a display area, such as a monitor screen or printed page. Each pixel is individually accessible.
What is POA ?
Portable Object Adapter. A CORBA standard for building server-side applications that are portable across heterogeneous ORBs.
What is primary key ?
An object that uniquely identifies an entity bean within a home
What is primitive type ?
A variable data type in which the variable's value is of the appropriate size and format for its type: a number, a character, or a Boolean value.
What is principal ?
The identity assigned to an entity as a result of authentication.
What is private ?
A Java keyword used in a method or variable declaration. It signifies that the method or variable can only be accessed by other elements of its class.
What is privilege ?
A security attribute that does not have the property of uniqueness and which may be shared by many principals. An example of a privilege is a group.
What is process ?
A virtual address space containing one or more threads.
What is property ?
Characteristics of an object that users can set, such as the color of a window.
What is profiles ?
A profile is a collection of Java APIs that complements one or more Java 2 Platform Editions by adding domain-specific capabilities. Profiles may also include other defined profiles. A profile implementation requires a Java 2 Platform Edition to create a complete development and deployment environment in a targeted vertical market. Each profile is subject to an associated set of compatibility requirements. Profiles may be usable on one or more editions.
Some examples of profiles within the Java 2 Platform, Micro Edition are:

* Personal Profile- for non-PC products that need to display Web-compatible Java-based content
* Java Card - for secure smart cards and other severely memory-constrained devices.
What is protected ?
A Java keyword used in a method or variable declaration. It signifies that the method or variable can only be accessed by elements residing in its class, subclasses, or classes in the same package.
What is public ?
A Java keyword used in a method or variable declaration. It signifies that the method or variable can be accessed by elements residing in other classes.
What is raster ?
A two-dimensional rectangular grid of pixels.
What is realm ?
See security policy domain. Also, a string, passed as part of an HTTP request during basic authentication, that defines a protection space. The protected resources on a server can be partitioned into a set of protection spaces, each with its own authentication scheme and/or authorization database
What is realm ?
A variable data type in which the variable's value is an address.
What is return ?
A Java keyword used to finish the execution of a method. It can be followed by a value required by the method definition.
What is SGML ?
Standardized Generalized Markup Language. An ISO/ANSI/ECMA standard that specifies a way to annotate text documents with information about types of sections of a document.
What is SOAP ?
The Simple Object Access Protocol (SOAP) uses a combination of XML-based data structuring and the Hyper Text Transfer Protocol (HTTP) to define a standardized method for invoking methods in objects distributed in diverse operating environments across the Internet.
What is SQL ?
Structured Query Language. The standardized relational database language for defining database objects and manipulating data.
What is static ?
A Java keyword used to define a variable as a class variable. Classes maintain one copy of class variables regardless of how many instances exist of that class. static can also be used to define a method as a class method. Class methods are invoked by the class instead of a specific instance, and can only operate on class variables.
What is static field ?
Another name for class variable.
What is static method ?
Another name for class method.
What is stream ?
A stream is simply a byte-stream of data that is sent from a sender to a receiver. There are two basic categories, so the java.io package includes two abstract classes (InputStream and OutputStream).
What is subclass ?
A class that is derived from a particular class, perhaps with one or more classes in between. See also superclass, supertype.
What is subtype ?
If type X extends or implements type Y, then X is a subtype of Y. See also supertype.
What is superclass ?
A class from which a particular class is derived, perhaps with one or more classes in between. See also subclass, subtype.
What is super ?
A Java keyword used to access members of a class inherited by the class in which it appears.
What is supertype ?
The supertypes of a type are all the interfaces and classes that are extended or implemented by that type. See also subtype, superclass.
What is switch ?
A Java keyword used to evaluate a variable that can later be matched with a value specified by the case keyword in order to execute a group of statements.
What is Swing ?
A collection of graphical user interface (GUI) components that runs uniformly on any native platform which supports the Java virtual machine*. Because they are written entirely in the Java programming language, these components may provide functionality above and beyond that provided by native-platform equivalents. (Contrast with AWT.)
What is synchronized ?
A keyword in the Java programming language that, when applied to a method or code block, guarantees that at most one thread at a time executes that code.
What is TCP/IP ?
Transmission Control Protocol based on IP. This is an Internet protocol that provides for the reliable delivery of streams of data from one host to another.
What is SGML ?
Standardized Generalized Markup Language. An ISO/ANSI/ECMA standard that specifies a way to annotate text documents with information about types of sections of a document.
What is SOAP ?
The Simple Object Access Protocol (SOAP) uses a combination of XML-based data structuring and the Hyper Text Transfer Protocol (HTTP) to define a standardized method for invoking methods in objects distributed in diverse operating environments across the Internet.
What is SQL ?
Structured Query Language. The standardized relational database language for defining database objects and manipulating data.
What is static ?
A Java keyword used to define a variable as a class variable. Classes maintain one copy of class variables regardless of how many instances exist of that class. static can also be used to define a method as a class method. Class methods are invoked by the class instead of a specific instance, and can only operate on class variables.
What is static field ?
Another name for class variable.
What is static method ?
Another name for class method.
What is stream ?
A stream is simply a byte-stream of data that is sent from a sender to a receiver. There are two basic categories, so the java.io package includes two abstract classes (InputStream and OutputStream).
What is subclass ?
A class that is derived from a particular class, perhaps with one or more classes in between. See also superclass, supertype.
What is subtype ?
If type X extends or implements type Y, then X is a subtype of Y. See also supertype.
What is superclass ?
A class from which a particular class is derived, perhaps with one or more classes in between. See also subclass, subtype.
What is super ?
A Java keyword used to access members of a class inherited by the class in which it appears.
What is supertype ?
The supertypes of a type are all the interfaces and classes that are extended or implemented by that type. See also subtype, superclass.
What is switch ?
A Java keyword used to evaluate a variable that can later be matched with a value specified by the case keyword in order to execute a group of statements.
What is Swing ?
A collection of graphical user interface (GUI) components that runs uniformly on any native platform which supports the Java virtual machine*. Because they are written entirely in the Java programming language, these components may provide functionality above and beyond that provided by native-platform equivalents. (Contrast with AWT.)
What is synchronized ?
A keyword in the Java programming language that, when applied to a method or code block, guarantees that at most one thread at a time executes that code.
What is TCP/IP ?
Transmission Control Protocol based on IP. This is an Internet protocol that provides for the reliable delivery of streams of data from one host to another.
What is URN ?
Uniform Resource Name. A unique identifier that identifies an entity, but doesn't tell where it is located. A system can use a URN to look up an entity locally before trying to find it on the Web. It also allows the Web location to change, while still allowing the entity to be found.
What is variable ?
An item of data named by an identifier. Each variable has a type, such as int or Object, and a scope. See also class variable, instance variable, local variable.
What is virtual machine ?
An abstract specification for a computing device that can be implemented in different ways, in software or hardware. You compile to the instruction set of a virtual machine much like you'd compile to the instruction set of a microprocessor. The Java virtual machine consists of a byte code instruction set, a set of registers, a stack, a garbage-collected heap, and an area for storing methods.
What is void ?
A Java keyword used in method declarations to specify that the method does not return any value. void can also be used as a nonfunctional statement.
What is volatile ?
A Java keyword used in variable declarations that specifies that the variable is modified asynchronously by concurrently running threads.
What is Web server ?
Software that provides services to access the Internet, an intranet, or an extranet. A Web server hosts Web sites, provides support for HTTP and other protocols, and executes server-side programs (such as CGI scripts or servlets) that perform certain functions.
What is while ?
A Java keyword used to declare a loop that iterates a block of statements. The loop's exit condition is specified as part of the while statement.
What is world readable files ?
Files on a file system that can be viewed (read) by any user. For example: files residing on Web servers can only be viewed by Internet users if their permissions have been set to world readable.
What is wrapper ?
An object that encapsulates and delegates to another object to alter its interface or behavior in some way.
What is XML ?
Extensible Markup Language. A markup language that allows you to define the tags (markup) needed to identify the data and text in XML documents.
What is ACID ?
The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.
What is Embedded Java Technology ?
The availability of Java 2 Platform, Micro Edition technology under a restrictive license agreement that allows a licensee to leverage certain Java technologies to create and deploy a closed-box application that exposes no APIs.
What is class method ?
A method that is invoked without reference to a particular object. Class methods affect the class as a whole, not a particular instance of the class. Also called a static method. See also instance method.
What is class variable ?
A data item associated with a particular class as a whole--not with particular instances of the class. Class variables are defined in class definitions. Also called a static field. See also instance variable.
What is constructor ?
A pseudo-method that creates an object. In the Java programming language, constructors are instance methods with the same name as their class. Constructors are invoked using the new keyword.
What is core packages ?
The required set of APIs in a Java platform edition which must be supported in any and all compatible implementations.

BEST EJB Interview Questions And Answers

What are the two important TCP Socket classes?
Socket and ServerSocket.
ServerSocket is used for normal two-way socket communication. Socket class allows us to read and write through the sockets. getInputStream() and getOutputStream() are the two methods available in Socket class.

What technologies are included in J2EE?
The main technologies in J2EE are: Enterprise JavaBeansTM (EJBsTM), JavaServer PagesTM (JSPsTM), Java Servlets, the Java Naming and Directory InterfaceTM (JNDITM), the Java Transaction API (JTA), CORBA, and the JDBCTM data access API.

What is the difference between EJB and Java beans?
EJB is a specification for J2EE server, not a product; Java beans may be a graphical component in IDE.

BEA WebLogic Interview Questions And Answers

What is BEA Weblogic?
BEA WebLogic is a J2EE application server and also an HTTP web server by BEA Systems of San Jose, California, for Unix, Linux, Microsoft Windows, and other platforms. WebLogic supports Oracle, DB2, Microsoft SQL Server, and other JDBC-compliant databases. WebLogic Server supports WS-Security and is compliant with J2EE 1.3.
BEA WebLogic Server is part of the BEA WebLogic Platform™. The other parts of WebLogic Platform are:
* Portal, which includes Commerce Server and Personalization Server (which is built on a BEA-produced Rete rules engine),
* WebLogic Integration,
* WebLogic Workshop, an IDE for Java, and
* JRockit, a JVM for Intel CPUs.