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
61. What is double ?
A Java keyword used to define a variable of type double.
62. 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.
63. What is DTD ?
Document Type Definition. A description of the structure and properties of a class of XML files.
64. 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.
65. 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.
66. 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.
67. What is enum ?
A Java keyword used to declare an enumerated type.
68. What is enumerated type ?
A type whose legal values consist of a fixed set of constants.
69. What is exception ?
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.
70. What is exception handler ?
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.