Java notes: The Java language, API, JDK, JRE, IDE

Q1) What is Java?

A1) Java is a powerful and versatile programming language for developing software for mobile devices, desktop computers, and servers.

Java is a simple, object-oriented, distributed, interpreted, robust, secure, architecture neutral, portable, high performance, multi threaded, and dynamic language.

Q2) What are Java applets?

Java initially became attractive because Java programs could be run from a web browser. Such programs are called applets.

Q3) Who invented Java? Which company owns Java now?

Java was developed by a team led by James Gosling at Sun Microsystems. Sun Microsystems was purchased by Oracle and so Oracle currently owns Java.

Q4) What is the Java Language specification and Java API?

A4) Java syntax is defined in the Java Language Specification and the Java libraries are defined in the Java application Program Interface (API).

Computer languages have strict rules of usage. If these rules aren’t followed then the computer will not be able to understand the program. The Java language specification and Java API define the Java standards.

The Java Language Specification is a technical definition of the Java programming language syntax and semantics (

The application programming interface (API), also known as library, contains predefined classes and interfaces for developing Java Programs. The API is still expanding (

Q5) Name and define the three Java editions.

A5) Java has three editions:

  1. Java Standard Edition (Java SE) to develop client side applications which can also run on the desktop.
  2. Java Enterprise Edition (Java EE) to develop server side applications such as Java servlets, Java server pages (JSP), and Java Server Faces (JSF)
  3. Java Micro Edition (Java ME) to develop applications for mobile devices.
Q6) What is JDK?

A6) The Java Development Kit (JDK) consists of a set of separate programs, each invoked from the command line for running, compiling, and testing Java Programs.

Q7) What is the JRE?

A7) The Java Runtime Environment (JRE) is a program used for running Java programs

Q8) What is an IDE?

A8) Instead of using JDK, you can use a Java Development Tool (like Netbeans, Eclipse, etc) software that provides an Integrated Development Environment (IDE) for developing Java programs quickly. Editing, compiling, building, debugging, and online help are some features that IDEs provide through a single graphical user interface.

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