Java Programming Language – Interview Questions & Answers (Page -1)

This section provides set of interview questions and answers on Java programming for job seeking and experienced person that can help to find jobs and improve you technical knowledge.

What is Java?

It’s a high level programming language, developed by the Sun MicroSystems in 1995. It is a fully based on OOPS (Object Oriented Programming System). Java is very reliable, secure and fast language, it is platform independent too. A Java program can be run on any system which has JVM.

What is JVM?

JVM stands for Java Virtual Machine; It is a virtual machine (abstract machine) which provides the runtime environment which Java bytecode can be executed.

What is bytecode?

Bytecode is the instruction set of the JVM, when a Java program compile, it generate an object code that is understable for the JVM i.e. we can say it’s a code for JVM which is generated by the Java Complier.

What are the JDK & JRE?

JRE stands for Java Runttime Environments, it is the environment of JVM & physical existence. JDK stands for Java Development Kit, it is the combination of JRE and Java tools, and with the help of these tools we can develop a Java Program.

What is JIT Compiler?

It is the Just-In-Time Compiler, It complies the similar functionality code also improves the performance. It reduces the compilation time as it can compile same functionality code in same time.

Is Java enables high performance and how?

Yes, Java enables the high performance as Java has Just-In-Compiler, which can compile same functionality byte code in same time. A Java program takes less time to compile than other programming language’s compiler.

What is the main difference between OOPS & OOBS programming system?

The language which does not support the concept of inheritance is known as Object Oriented Based System, while OOPS supports the all features of Object Oriented Programming System including inheritance. JavaScript, VBScript are the example of Object Oriented Based System (OOBS) programming Language.

What is the most important feature of Java?

Java is basically known for the platform independency, "Java is a platform important language" It is the most important feature of Java.

What is "Platform Independency" in Java?

Here platform stands for Operating System on which program is being executed. A Java program, which is written on one platform (OS – Like Windows, Linux etc) can also run on another platform.

Which class is super class in Java Program?

Object class, is a super class in Java.

Does Java support pointers?

No, Java does not support pointers as pointer can access the memory locations directly. Hence pointers are not used in Java Programming, but there is an alternative of pointers in Java that is references. references are the different from pointers, these store the address of objects.

Why CLASSPATH and PATH are used?

These are two environment variables that are used to set an environment to run Java Programs on machine.
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