J2SE Interview Questions & Answers

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J2SE Interview Questions & Answers

Are you preparing for J2SE interview? If yes, then we’ve a solution to win your ideal job. J2SE is the basic standard edition of Java Platform. Standard programs are made with Java. It is the premier platform for swiftly developing and deploying portal and secure applications that run on desktop and server spanning most operating systems. Looking for a job can be cumbersome and tiring, especially when you are not aware of how to apply and where to search and how to prepare well for the job interviews. Wisdomjobs framed J2SE job interview questions and answers to make it easier for your interview preparation. If you are expertise in Java programming language, then multiple job opportunities are available for your reference.

J2SE Interview Questions

J2SE Interview Questions
    1. Question 1. What Is J2se?

      Answer :

      J2SE consists of two components: Core Java and Desktop Java. Core Java provides back-end functionality, while Desktop Java provides GUI (Graphical User Interface) functionality.

      J2SE contains both the J2SE Development Kit(JDK) and the Java Runtime Environment(JRE).

      javaSE(java Standard Edition)deals with developing standalone application and also basic programs for the network. j2se cotains two parts

      1. core java
      2. Advanced java.

    2. Question 2. What Is Java 2 Sdk, Standard Edition ?

      Answer :

      The Software Development Kit (SDK) is development environment for building applications, applets, and components using the Java programming language. This SDK provides a reference implementation of the J2SE platform.

    3. Question 3. What Is Java Naming And Directory Interface (jndi) ?

      Answer :

      A set of APIs that assists with the interfacing to multiple naming and directory services.

    4. Question 4. What Is Java Compatibility Kit (jck) ?

      Answer :

      A test suite, a set of tools, and other requirements used to certify a Java platform implementation conformant both to the applicable Java platform specifications and to Java Software reference implementations.

    5. Question 5. What Is Abstract ?

      Answer :

      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.

    6. Question 6. What Is Abstract Class ?

      Answer :

      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.

    7. Question 7. What Is Abstract Method ?

      Answer :

      A method that has no implementation.

    8. Question 8. What Is Abstract Window Toolkit (awt) ?

      Answer :

      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.

    9. Question 9. What Is Access Control ?

      Answer :

      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.

    10. Question 10. What Is Acid ?

      Answer :

      The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.

    11. Question 11. What Is Actual Parameter List ?

      Answer :

      The arguments specified in a particular method call. See also formal parameter list.

    12. Question 12. What Is Api ?

      Answer :

      Application Programming Interface. The specification of how a programmer writing an application accesses the behavior and state of classes and objects.

    13. Question 13. What Is Applet ?

      Answer :

      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.

    14. Question 14. What Is Ascii ?

      Answer :

      American Standard Code for Information Interchange. A standard assignment of 7-bit numeric codes to characters. See also Unicode.

    15. Question 15. What Is Atomic ?

      Answer :

      Refers to an operation that is never interrupted or left in an incomplete state under any circumstance.

    16. Question 16. What Is Authentication ?

      Answer :

      The process by which an entity proves to another entity that it is acting on behalf of a specific identity.

    17. Question 17. What Is Autoboxing ?

      Answer :

      Automatic conversion between reference and primitive types.

    18. Question 18. What Is Bean ?

      Answer :

      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.

    19. Question 19. What Is Binary Operator ?

      Answer :

      An operator that has two arguments.

    20. Question 20. What Is Bitwise Operator ?

      Answer :

      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 (~).

    21. Question 21. What Is Block ?

      Answer :

      In the Java programming language, any code between matching braces. Example: { x = 1; }.

    22. Question 22. What Is Boolean ?

      Answer :

      Refers to an expression or variable that can have only a true or false value. The Java programming language provides the boolean type and the literal values true and false.

    23. Question 23. What Is Break ?

      Answer :

      A Java keyword used to resume program execution at the statement immediately following the current statement. If followed by a label, the program resumes execution at the labeled statement.

    24. Question 24. What Is Bytecode ?

      Answer :

      Machine-independent code generated by the Java compiler and executed by the Java interpreter.

    25. Question 25. What Is Case ?

      Answer :

      A Java keyword that defines a group of statements to begin executing if a value specified matches the value defined by a preceding switch keyword.

    26. Question 26. What Is Casting ?

      Answer :

      Explicit conversion from one data type to another.

    27. Question 27. What Is Catch ?

      Answer :

      A Java keyword used to declare a block of statements to be executed in the event that a Java exception, or run time error, occurs in a preceding try block.

    28. Question 28. What Is "abstract Schema" ?

      Answer :

      The part of an entity bean's deployment descriptor that defines the bean's persistent fields and relationships.

    29. Question 29. What Is "abstract Schema Name" ?

      Answer :

      A logical name that is referenced in EJB QL queries.

    30. Question 30. What Is "access Control" ?

      Answer :

      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.

    31. Question 31. What Is "acid" ?

      Answer :

      The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.

    32. Question 32. What Is "activation" ?

      Answer :

      The process of transferring an enterprise bean from secondary storage to memory. (See passivation.)

    33. Question 33. What Is "anonymous Access" ?

      Answer :

      Accessing a resource without authentication.

    34. Question 34. What Is Class ?

      Answer :

      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.

    35. Question 35. What Is Class Method ?

      Answer :

      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.

    36. Question 36. What Is Class Variable ?

      Answer :

      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.

    37. Question 37. What Is Classpath ?

      Answer :

      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.

    38. Question 38. What Is Client ?

      Answer :

      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.

    39. Question 39. What Is Codebase ?

      Answer :

      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.

    40. Question 40. What Is Comment ?

      Answer :

      In a program, explanatory text that is ignored by the compiler. In programs written in the Java programming language, comments are delimited using // or /*...*/.

    41. Question 41. What Is Commit ?

      Answer :

      The point in a transaction when all updates to any resources involved in the transaction are made permanent.

    42. Question 42. What Is Compilation Unit ?

      Answer :

      The smallest unit of source code that can be compiled. In the current implementation of the Java platform, the compilation unit is a file.

    43. Question 43. What Is Compiler ?

      Answer :

      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.

    44. Question 44. What Is Compositing ?

      Answer :

      The process of superimposing one image on another to create a single image.

    45. Question 45. What Is Constructor ?

      Answer :

      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.

    46. Question 46. What Is Const ?

      Answer :

      A reserved Java keyword not used by current versions of the Java programming language.

    47. Question 47. What Is Continue ?

      Answer :

      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.

    48. Question 48. What Is Conversational State ?

      Answer :

      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.

    49. Question 49. What Is Corba ?

      Answer :

      Common Object Request Broker Architecture. A language independent, distributed object model specified by the Object Management Group (OMG).

    50. Question 50. What Is Core Class ?

      Answer :

      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.

    51. Question 51. What Is Core Packages ?

      Answer :

      The required set of APIs in a Java platform edition which must be supported in any and all compatible implementations.

    52. Question 52. What Is Credentials ?

      Answer :

      The information describing the security attributes of a principal. Credentials can be acquired only through authentication or delegation.

    53. Question 53. What Is Critical Section ?

      Answer :

      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.

    54. Question 54. What Is Declaration ?

      Answer :

      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.

    55. Question 55. What Is Default ?

      Answer :

      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.

    56. Question 56. What Is Definition ?

      Answer :

      A declaration that reserves storage (for data) or provides implementation (for methods). See also declaration.

    57. Question 57. What Is Delegation ?

      Answer :

      An act whereby one principal authorizes another principal to use its identity or privileges with some restrictions.

    58. Question 58. What Is Deprecation ?

      Answer :

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

    59. Question 59. What Is Distributed ?

      Answer :

      Running in more than one address space.

    60. Question 60. What Is Distributed Application ?

      Answer :

      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).

    61. Question 61. What Is Do ?

      Answer :

      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.

    62. Question 62. What Is Dom ?

      Answer :

      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.

    63. Question 63. What Is Double ?

      Answer :

      A Java keyword used to define a variable of type double.

    64. Question 64. What Is Double Precision ?

      Answer :

      In the Java programming language specification, describes a floating point number that holds 64 bits of data. See also single precision.

    65. Question 65. What Is Dtd ?

      Answer :

      Document Type Definition. A description of the structure and properties of a class of XML files.

    66. Question 66. What Is Else ?

      Answer :

      A Java keyword used to execute a block of statements in the case that the test condition with the if keyword evaluates to false.

    67. Question 67. What Is Embedded Java Technology ?

      Answer :

      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.

    68. Question 68. What Is Encapsulation ?

      Answer :

      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.

    69. Question 69. What Is Enum ?

      Answer :

      A Java keyword used to declare an enumerated type.

    70. Question 70. What Is Enumerated Type ?

      Answer :

      A type whose legal values consist of a fixed set of constants.

    71. Question 71. What Is Exception ?

      Answer :

      An event during program execution that prevents the program from continuing normally; generally, an error. The Java programming language supports exceptions with the try, catch, and throw keywords. See also exception handler.

    72. Question 72. What Is Exception Handler ?

      Answer :

      A block of code that reacts to a specific type of exception. If the exception is for an error that the program can recover from, the program can resume executing after the exception handler has executed.

    73. Question 73. What Is Executable Content ?

      Answer :

      An application that runs from within an HTML file. See also applet.

    74. Question 74. What Is Extends ?

      Answer :

      Class X extends class Y to add functionality, either by adding fields or methods to class Y, or by overriding methods of class Y. An interface extends another interface by adding methods. Class X is said to be a subclass of class Y. See also derived from.

    75. Question 75. What Is Field ?

      Answer :

      A data member of a class. Unless specified otherwise, a field is not static.

    76. Question 76. What Is Final ?

      Answer :

      A Java keyword. You define an entity once and cannot change it or derive from it later. More specifically: a final class cannot be subclassed, a final method cannot be overridden and a final variable cannot change from its initialized value.

    77. Question 77. What Is Finally ?

      Answer :

      A Java keyword that executes a block of statements regardless of whether a Java Exception, or run time error, occurred in a block defined previously by the try keyword.

    78. Question 78. What Is Float ?

      Answer :

      A Java keyword used to define a floating point number variable.

    79. Question 79. What Is For ?

      Answer :

      A Java keyword used to declare a loop that reiterates statements. The programmer can specify the statements to be executed, exit conditions, and initialization variables for the loop.

    80. Question 80. What Is Ftp ?

      Answer :

      File Transfer Protocol. FTP, which is based on TCP/IP, enables the fetching and storing of files between hosts on the Internet.

    81. Question 81. What Is Formal Parameter List ?

      Answer :

      The parameters specified in the definition of a particular method. See also actual parameter list.

    82. Question 82. What Is Garbage Collection ?

      Answer :

      The automatic detection and freeing of memory that is no longer in use. The Java runtime system performs garbage collection so that programmers never explicitly free objects.

    83. Question 83. What Is Generic ?

      Answer :

      A class, interface, or method that declares one or more type variables. These type variables are known as type parameters. A generic declaration defines a set of parameterized types, one for each possible invocation of the type parameter section. At runtime, all of these parameterized types share the same class, interface, or method.

    84. Question 84. What Is Goto ?

      Answer :

      This is a reserved Java keyword. However, it is not used by current versions of the Java programming language.

    85. Question 85. What Is Gui ?

      Answer :

      Graphical User Interface. Refers to the techniques involved in using graphics, along with a keyboard and a mouse, to provide an easy-to-use interface to some program.

    86. Question 86. What Is Hexadecimal ?

      Answer :

      The numbering system that uses 16 as its base. The marks 0-9 and a-f (or equivalently A-F) represent the digits 0 through 15. In programs written in the Java programming language, hexadecimal numbers must be preceded with 0x. See also octal.

    87. Question 87. What Is Group ?

      Answer :

      A collection of principals within a given security policy domain.

    88. Question 88. What Is Hierarchy ?

      Answer :

      A classification of relationships in which each item except the top one (known as the root) is a specialized form of the item above it. Each item can have one or more items below it in the hierarchy. In the Java class hierarchy, the root is the Object class.

    89. Question 89. What Is Html ?

      Answer :

      Hypertext Markup Language. This is a file format, based on SGML, for hypertext documents on the Internet. It is very simple and allows for the embedding of images, sounds, video streams, form fields and simple text formatting. References to other objects are embedded using URLs.

    90. Question 90. What Is Http ?

      Answer :

      Hypertext Transfer Protocol. The Internet protocol, based on TCP/IP, used to fetch hypertext objects from remote hosts. See also TCP/IP.

    91. Question 91. What Is Https ?

      Answer :

      Hypertext Transfer Protocol layered over the SSL protocol.

    92. Question 92. What Is Idl ?

      Answer :

      Interface Definition Language. APIs written in the Java programming language that provide standards-based interoperability and connectivity with CORBA (Common Object Request Broker Architecture).

    93. Question 93. What Is Identifier ?

      Answer :

      The name of an item in a program written in the Java programming language.

    94. Question 94. What Is Iiop ?

      Answer :

      Internet Inter-ORB Protocol. A protocol used for communication between CORBA object request brokers.

    95. Question 95. What Is If ?

      Answer :

      A Java keyword used to conduct a conditional test and execute a block of statements if the test evaluates to true.

    96. Question 96. What Is Impersonation ?

      Answer :

      An act whereby one entity assumes the identity and privileges of another entity without restrictions and without any indication visible to the recipients of the impersonator's calls that delegation has taken place. Impersonation is a case of simple delegation.

    97. Question 97. What Is Implements ?

      Answer :

      A Java keyword included in the class declaration to specify any interfaces that are implemented by the current class.

    98. Question 98. What Is Import ?

      Answer :

      A Java keyword used at the beginning of a source file that can specify classes or entire packages to be referred to later without including their package names in the reference.

    99. Question 99. What Is Inheritance ?

      Answer :

      The concept of classes automatically containing the variables and methods defined in their super types. See also super class, subclass.

    100. Question 100. What Is Instance ?

      Answer :

      An object of a particular class. In programs written in the Java programming language, an instance of a class is created using the new operator followed by the class name.

    101. Question 101. What Is Instance Method ?

      Answer :

      Any method that is invoked with respect to an instance of a class. Also called simply a method. See also class method.

    102. Question 102. What Is Instance Variable ?

      Answer :

      Any item of data that is associated with a particular object. Each instance of a class has its own copy of the instance variables defined in the class. Also called a field. See also class variable.

    103. Question 103. What Is Instanceof ?

      Answer :

      A two-argument Java keyword that tests whether the runtime type of its first argument is assignment compatible with its second argument.

    104. Question 104. What Is Int ?

      Answer :

      A Java keyword used to define a variable of type integer.

    105. Question 105. What Is Interface ?

      Answer :

      A Java keyword used to define a collection of method definitions and constant values. It can later be implemented by classes that define this interface with the "implements" keyword.

    106. Question 106. What Is Internet ?

      Answer :

      An enormous network consisting of literally millions of hosts from many organizations and countries around the world. It is physically put together from many smaller networks and data travels by a common set of protocols.

    107. Question 107. What Is Ip ?

      Answer :

      Internet Protocol. The basic protocol of the Internet. It enables the unreliable delivery of individual packets from one host to another. It makes no guarantees about whether or not the packet will be delivered, how long it will take, or if multiple packets will arrive in the order they were sent. Protocols built on top of this add the notions of connection and reliability.

    108. Question 108. What Is Interpreter ?

      Answer :

      A module that alternately decodes and executes every statement in some body of code. The Java interpreter decodes and executes bytecode for the Java virtual machine1. See also compiler, runtime system.

    109. Question 109. What Is Jar ?

      Answer :

      JAR (Java Archive) is a platform-independent file format that aggregates many files into one. Multiple applets written in the Java programming language, and their requisite components (.class files, images, sounds and other resource files) can be bundled in a JAR file and subsequently downloaded to a browser in a single HTTP transaction. It also supports file compression and digital signatures.

    110. Question 110. What Is Java ?

      Answer :

      A set of technologies for creating and safely running software programs in both stand-alone and networked environments.

    111. Question 111. What Is Java 2 Platform ?

      Answer :

      The second generation of the Java platform. (The first generation was the JDK.) Also see "Java Platform" and "Java Platform Editions".

    112. Question 112. What Is Java Apis For Integrated Networks (jain) ?

      Answer :

      Enables the rapid development of Next Generation telecom products and services on the Java platform.

    113. Question 113. What Is Java Card Api ?

      Answer :

      An ISO 7816-4 compliant application environment focused on smart cards.

    114. Question 114. What Is Java Database Connectivity (jdbc) ?

      Answer :

      An industry standard for database-independent connectivity between the Java platform and a wide range of databases. The JDBC provides a call-level API for SQL-based database access.

    115. Question 115. What Is Java Development Kit (jdk) ?

      Answer :

      A software development environment for writing applets and applications in the Java programming language. Technically, the JDK is the correct name for all versions of the Java platform from 1.0 to 1.1.x.

    116. Question 116. What Is Java Foundation Classes (jfc) ?

      Answer :

      An extension that adds graphical user interface class libraries to the Abstract Windowing Toolkit (AWT)

    117. Question 117. What Is Java Idl ?

      Answer :

      Java Interface Definition Language.

    118. Question 118. What Is Java Interface Definition Language (idl) ?

      Answer :

      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.

    119. Question 119. What Is Java Media Apis ?

      Answer :

      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.

    120. Question 120. What Is Java Media Framework ?

      Answer :

      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.

    121. Question 121. What Is Java Native Interface ?

      Answer :

      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.

    122. Question 122. What Is Java Platform ?

      Answer :

      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.

    123. Question 123. What Is Java Platform Editions ?

      Answer :

      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.

    124. Question 124. What Is Java Remote Method Invocation (rmi) ?

      Answer :

      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.

    125. Question 125. What Is Java Runtime Environment (jre) ?

      Answer :

      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.

    126. Question 126. What Is Java Virtual Machine ?

      Answer :

      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).

    127. Question 127. What Is Javabeans ?

      Answer :

      A portable, platform-independent reusable component model. A component that conforms to this model is called a bean.

    128. Question 128. What Is Javacheck ?

      Answer :

      A tool for checking compliance of applications and applets to a specification.

    129. Question 129. What Is Javasafe ?

      Answer :

      A tool for tracking and managing source file changes, written in Java.

    130. Question 130. What Is Javascript ?

      Answer :

      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.

    131. Question 131. What Is Javaspaces ?

      Answer :

      A technology that provides distributed persistence and data exchange mechanisms for code in Java.

    132. Question 132. What Is Jdbc ?

      Answer :

      Java Database Connectivity.

    133. Question 133. What Is Jdk ?

      Answer :

      Java Development Kit. A software development environment for writing applets and application in Java .

    134. Question 134. What Is Jfc ?

      Answer :

      Java Foundation Classes.

    135. Question 135. What Is Jini Technology ?

      Answer :

      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.

    136. Question 136. What Is Jndi ?

      Answer :

      Java Naming and Directory Interface.

    137. Question 137. What Is Jni ?

      Answer :

      Java Native Interface.

    138. Question 138. What Is Jre ?

      Answer :

      Java Runtime Environment.

    139. Question 139. What Is Just-in-time (jit) Compiler ?

      Answer :

      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.

    140. Question 140. What Is Jvm ?

      Answer :

      Java Virtual Machine (JVM).

    141. Question 141. What Is Keyword ?

      Answer :

      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.

    142. Question 142. What Is Lexical ?

      Answer :

      Pertaining to how the characters in source code are translated into tokens that the compiler can understand.

    143. Question 143. What Is Linker ?

      Answer :

      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.

    144. Question 144. What Is Literal ?

      Answer :

      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.

    145. Question 145. What Is Local Variable ?

      Answer :

      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.

    146. Question 146. What Is Long ?

      Answer :

      A Java keyword used to define a variable of type long.

    147. Question 147. What Is Member ?

      Answer :

      A field or method of a class. Unless specified otherwise, a member is not static.

    148. Question 148. What Is Method ?

      Answer :

      A function defined in a class. See also instance method, class method. Unless specified otherwise, a method is not static.

    149. Question 149. What Is Multithreaded ?

      Answer :

      Describes a program that is designed to have parts of its code execute concurrently. See also thread.

    150. Question 150. What Is Native ?

      Answer :

      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.

    151. Question 151. What Is New ?

      Answer :

      A Java keyword used to create an instance of a class.

    152. Question 152. What Is Null ?

      Answer :

      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.

    153. Question 153. What Is Object ?

      Answer :

      The principal building blocks of object-oriented programs. Each object is a programming unit consisting of data (instance variables) and functionality (instance methods).

    154. Question 154. What Is Object-oriented Design ?

      Answer :

      A software design method that models the characteristics of abstract or real objects using classes and objects.

    155. Question 155. What Is Octal What Is Object-oriented Design ?

      Answer :

      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.

    156. Question 156. What Is Optional Packages ?

      Answer :

      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.

    157. Question 157. What Is Orb ?

      Answer :

      Object Request Broker. A library than enables CORBA objects to locate and communicate with one another.

    158. Question 158. What Is Os Principal ?

      Answer :

      A principal native to the operating system on which the Java platform is executing.

    159. Question 159. What Is Ots ?

      Answer :

      Object Transaction Service. A definition of the interfaces that permit CORBA objects to participate in transactions.

    160. Question 160. What Is Overloading ?

      Answer :

      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.

    161. Question 161. What Is Overriding ?

      Answer :

      Providing a different implementation of a method in a subclass of the class that originally defined the method.

    162. Question 162. What Is Package ?

      Answer :

      A group of types. Packages are declared with the package keyword.

    163. Question 163. What Is Peer ?

      Answer :

      In networking, any functional unit in the same layer as another entity.

    164. Question 164. What Is Persistence ?

      Answer :

      The protocol for transferring the state of a bean between its instance variables and an underlying database.

    165. Question 165. What Is Pixel ?

      Answer :

      The picture element on a display area, such as a monitor screen or printed page. Each pixel is individually accessible.

    166. Question 166. What Is Poa ?

      Answer :

      Portable Object Adapter. A CORBA standard for building server-side applications that are portable across heterogeneous ORBs.

    167. Question 167. What Is Primary Key ?

      Answer :

      An object that uniquely identifies an entity bean within a home .

    168. Question 168. What Is Primitive Type ?

      Answer :

      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.

    169. Question 169. What Is Principal ?

      Answer :

      The identity assigned to an entity as a result of authentication.

    170. Question 170. What Is Private ?

      Answer :

      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.

    171. Question 171. What Is Privilege ?

      Answer :

      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.

    172. Question 172. What Is Process ?

      Answer :

      A virtual address space containing one or more threads.

    173. Question 173. What Is Property ?

      Answer :

      Characteristics of an object that users can set, such as the color of a window.

    174. Question 174. What Is Profiles ?

      Answer :

      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.

    175. Question 175. Some Examples Of Profiles Within The Java 2 Platform, Micro Edition Are:

      Answer :

      * 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.

    176. Question 176. What Is Protected ?

      Answer :

      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.

    177. Question 177. What Is Public ?

      Answer :

      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.

    178. Question 178. What Is Raster ?

      Answer :

      A two-dimensional rectangular grid of pixels.

    179. Question 179. What Is Realm ?

      Answer :

      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.

    180. Question 180. What Is Return ?

      Answer :

      A Java keyword used to finish the execution of a method. It can be followed by a value required by the method definition.

    181. Question 181. What Is Rmi ?

      Answer :

      See Java Remote Method Invocation.

    182. Question 182. What Is Rollback ?

      Answer :

      The point in a transaction when all updates to any databases involved in the transaction are reversed.

    183. Question 183. What Is Root ?

      Answer :

      In a hierarchy of items, the one item from which all other items are descended. The root item has nothing above it in the hierarchy.

    184. Question 184. What Is Rpc ?

      Answer :

      Remote Procedure Call. Executing what looks like a normal procedure call (or method invocation) by sending network packets to some remote host.

    185. Question 185. What Is Runtime System ?

      Answer :

      The software environment in which programs compiled for the Java virtual machine1 can run. The runtime system includes all the code necessary to load programs written in the Java programming language, dynamically link native methods, manage memory, handle exceptions, and an implementation of the Java virtual machine, which may be a Java interpreter.

    186. Question 186. What Is Sax ?

      Answer :

      Simple API for XML. An event-driven, serial-access mechanism for accessing XML documents.

    187. Question 187. What Is Sandbox ?

      Answer :

      Comprises a number of cooperating system components, ranging from security managers that execute as part of the application, to security measures designed into the Java virtual machine1 and the language itself. The sandbox ensures that an untrusted, and possibly malicious, application cannot gain access to system resources.

    188. Question 188. What Is Scope ?

      Answer :

      A characteristic of an identifier that determines where the identifier can be used. Most identifiers in the Java programming environment have either class or local scope. Instance and class variables and methods have class scope; they can be used outside the class and its subclasses only by prefixing them with an instance of the class or (for class variables and methods) with the class name. All other variables are declared within methods and have local scope; they can be used only within the enclosing block.

    189. Question 189. What Is Secure Socket Layer (ssl) ?

      Answer :

      A protocol that allows communication between a Web browser and a server to be encrypted for privacy.

    190. Question 190. What Is Security Attributes ?

      Answer :

      A set of properties associated with a principal. Security attributes can be associated with a principal by an authentication protocol.

    191. Question 191. What Is Security Context ?

      Answer :

      An object that encapsulates the shared state information regarding security between two entities.

    192. Question 192. What Is Security Policy Domain ?

      Answer :

      A scope over which security policies are defined and enforced by a security administrator. A security policy domain has the following characteristics:
      It has a collection of users (or principals).
      It uses a well defined authentication protocol(s) for authenticating users (or principals).
      It may have groups to simplify setting of security policies.

    193. Question 193. What Is Security Technology Domain ?

      Answer :

      A scope over which the same security mechanism is used to enforce a security policy. Multiple security policy domains can exist within a single technology domain.

    194. Question 194. What Is Serialization ?

      Answer :

      The encoding of objects, and the objects reachable from them, into a stream of bytes and the complementary reconstruction of the object graph from the stream.

    195. Question 195. What Is Short ?

      Answer :

      A Java keyword used to define a variable of type short.

    196. Question 196. What Is Single Precision ?

      Answer :

      In the Java language specification, describes a floating point number with 32 bits of data. See also double precision.

    197. Question 197. What Is Sgml ?

      Answer :

      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.

    198. Question 198. What Is Soap ?

      Answer :

      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.

    199. Question 199. What Is Sql ?

      Answer :

      Structured Query Language. The standardized relational database language for defining database objects and manipulating data.

    200. Question 200. What Is Static ?

      Answer :

      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.

    201. Question 201. What Is Static Field ?

      Answer :

      A static field is a class field, which means that its data is stored in one location in memory, no matter how many objects are created from its class. In fact, you can use a static field to keep track of how many objects have been created from a particular class.

    202. Question 202. What Is Static Method ?

      Answer :

      Methods declared with the keyword static as modifier are called static methods or class methods.

      There are two types of methods:

      • Instance methods : associated with an object and use the instance variables of that object. This is the default.
      • Static methods : use no instance variables of any object of the class they are defined in. If you define a method to be static, you will be given a rude message by the compiler if you try to access any instance variables. You can access static variables, but except for constants, this is unusual. Static methods typically take all they data from parameters and compute something from those parameters, with no reference to variables. This is typical of methods which do some kind of generic calculation. A good example of this are the many utility methods in the predefined Math class.

    203. Question 203. What Is Stream ?

      Answer :

      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).

    204. Question 204. What Is Subclass ?

      Answer :

      A class that is derived from a particular class, perhaps with one or more classes in between.

    205. Question 205. What Is Subtype ?

      Answer :

      If type X extends or implements type Y, then X is a subtype of Y.

    206. Question 206. What Is Superclass ?

      Answer :

      A class from which a particular class is derived, perhaps with one or more classes in between.

    207. Question 207. What Is Super ?

      Answer :

      A Java keyword used to access members of a class inherited by the class in which it appears.

    208. Question 208. What Is Supertype ?

      Answer :

      The supertypes of a type are all the interfaces and classes that are extended or implemented by that type.

    209. Question 209. What Is Switch ?

      Answer :

      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.

    210. Question 210. What Is Swing ?

      Answer :

      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.

    211. Question 211. What Is Synchronized ?

      Answer :

      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.

    212. Question 212. What Is Tcp/ip ?

      Answer :

      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.

    213. Question 213. What Is Technology Compatibility Kit (tck) ?

      Answer :

      A test suite, a set of tools, and other requirements used to certify an implementation of a particular Sun technology conformant both to the applicable specifications and to Sun or Sun-designated reference implementations.

    214. Question 214. What Is Thin Client ?

      Answer :

      A system that runs a very light operating system with no local system administration and executes applications delivered over the network.

    215. Question 215. What Is 'this' ?

      Answer :

      A Java keyword 'that' can be used to represent an instance of the class in which it appears. 'this' can be used to access class variables and methods.

    216. Question 216. What Is Thread ?

      Answer :

      The basic unit of program execution. A process can have several threads running concurrently, each performing a different job, such as waiting for events or performing a time-consuming job that the program doesn't need to complete before going on. When a thread has finished its job, the thread is suspended or destroyed.

    217. Question 217. What Is Throw ?

      Answer :

      A Java keyword that allows the user to throw an exception or any class that implements the "throwable" interface.

    218. Question 218. What Is Throws ?

      Answer :

      A Java keyword used in method declarations that specify which exceptions are not handled within the method but rather passed to the next higher level of the program.

    219. Question 219. What Is Transaction ?

      Answer :

      An atomic unit of work that modifies data. A transaction encloses one or more program statements, all of which either complete or roll back. Transactions enable multiple users to access the same data concurrently.

    220. Question 220. What Is Transaction Isolation Level ?

      Answer :

      The degree to which the intermediate state of the data being modified by a transaction is visible to other concurrent transactions and data being modified by other transactions is visible to it.

    221. Question 221. What Is Transaction Manager ?

      Answer :

      Provides the services and management functions required to support transaction demarcation, transactional resource management, synchronization, and transaction context propagation.

    222. Question 222. What Is Transient ?

      Answer :

      A keyword in the Java programming language that indicates that a field is not part of the serialized form of an object. When an object is serialized, the values of its transient fields are not included in the serial representation, while the values of its non-transient fields are included.

    223. Question 223. What Is Try ?

      Answer :

      A Java keyword that defines a block of statements that may throw a Java language exception. If an exception is thrown, an optional catch block can handle specific exceptions thrown within the try block. Also, an optional finally block will be executed regardless of whether an exception is thrown or not.

    224. Question 224. What Is Type ?

      Answer :

      A class or interface.

    225. Question 225. What Is Unicode ?

      Answer :

      A 16-bit character set defined by ISO 10646. See also ASCII. All source code in the Java programming environment is written in Unicode.

    226. Question 226. What Is Uri ?

      Answer :

      Uniform Resource Identifier. A compact string of characters for identifying an abstract or physical resource. A URI is either a URL or a URN. URLs and URNs are concrete entities that actually exist; A URI is an abstract superclass.

    227. Question 227. What Is Url ?

      Answer :

      Uniform Resource Locator. A standard for writing a text reference to an arbitrary piece of data in the WWW. A URL looks like "protocol://host/localinfo" where protocol specifies a protocol to use to fetch the object (like HTTP or FTP), host specifies the Internet name of the host on which to find it, and localinfo is a string (often a file name) passed to the protocol handler on the remote host.

    228. Question 228. What Is Urn ?

      Answer :

      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.

    229. Question 229. What Is Variable ?

      Answer :

      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.

    230. Question 230. What Is Virtual Machine ?

      Answer :

      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.

    231. Question 231. What Is Void ?

      Answer :

      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.

    232. Question 232. What Is Volatile ?

      Answer :

      A Java keyword used in variable declarations that specifies that the variable is modified asynchronously by concurrently running threads.

    233. Question 233. What Is Web Server ?

      Answer :

      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.

    234. Question 234. What Is While ?

      Answer :

      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.

    235. Question 235. What Is World Readable Files ?

      Answer :

      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.

    236. Question 236. What Is Wrapper ?

      Answer :

      An object that encapsulates and delegates to another object to alter its interface or behavior in some way.

    237. Question 237. What Is Xml ?

      Answer :

      Extensible Markup Language. A markup language that allows you to define the tags (markup) needed to identify the data and text in XML documents.

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