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
151. What is new ?
A Java keyword used to create an instance of a class.
152. 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.
153. 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.
154. What is object-oriented design ?
A software design method that models the characteristics of abstract or real objects using classes and objects.
155. 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.
156. 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.
157. What is ORB ?
Object Request Broker. A library than enables CORBA objects to locate and communicate with one another.
158. What is OS principal ?
A principal native to the operating system on which the Java platform is executing.
159. What is OTS ?
Object Transaction Service. A definition of the interfaces that permit CORBA objects to participate in transactions.
160. 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.