Technical interview questions and answers are essential for J2SE Interviews because core Java concepts form the foundation of all Java-based development. Companies test your knowledge of OOP principles, exceptions, packages, JVM architecture, threading, collections, and file handling. These topics commonly appear in placement drives and technical interviews conducted by TCS, Infosys, Wipro, Cognizant, and Capgemini. Understanding J2SE concepts helps freshers and job seekers prepare for both Java developer roles and advanced J2EE/Java EE interviews. This guide features the most commonly asked J2SE interview questions with answers explained in simple language. Preparing these questions will strengthen your Java basics and improve your performance in coding tests and technical rounds.
Java programmers should advance their enterprise skills by studying J2EE frameworks and mastering EJB components for distributed applications
Showing 10 of 237 questions
211. 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.
212. 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.
213. What is Technology Compatibility Kit (TCK) ?
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. What is thin client ?
A system that runs a very light operating system with no local system administration and executes applications delivered over the network.
215. What is 'this' ?
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. What is thread ?
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. See also process.
217. What is throw ?
A Java keyword that allows the user to throw an exception or any class that implements the "throwable" interface.
218. What is transaction ?
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.
219. What is transaction isolation level ?
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.
220. What is transaction manager ?
Provides the services and management functions required to support transaction demarcation, transactional resource management, synchronization, and transaction context propagation.