Java is an object-oriented, class-based, concurrent, secured and general-purpose computer-programming language.
Devices that uses Java
According to Sun, 3 billion devices run Java
1. Desktop Applications such as acrobat reader, media player, antivirus, etc.
2. Web Applications such as irctc.co.in, javatpoint.com, etc.
3. Enterprise Applications such as banking applications.
4. Mobile
5. Embedded System
6. Smart Card
7. Robotics
8. Games, etc.
Types of Java Applications
There are mainly 4 types of applications that can be created using Java programming:
1. Standalone Application: are also known as desktop applications or window-based applications. These are traditional software that we need to install on every machine. Examples of standalone application are Media player, antivirus, etc. AWT and Swing are used in Java for creating standalone applications.
2. Web Application: that runs on the server side and creates a dynamic page is called a web application. Currently, Servlet, JSP, Struts, Spring, Hibernate, JSF, etc. technologies are used for creating web applications in Java.
3. Enterprise Application: is distributed in nature, such as banking applications, etc. is called enterprise application. It has advantages of the high-level security, load balancing, and clustering. In Java, EJB is used for creating enterprise applications.
4. Mobile Application: which is created for mobile devices is called a mobile application. Currently, Android and Java ME are used for creating mobile applications.
Java Platforms / Editions
There are 4 platforms or editions of Java:
1. Java SE (Java Standard Edition) is a Java programming platform. It includes Java programming APIs such as java.lang, java.io, java.net, java.util, java.sql, java.math etc. It includes core topics like OOPs, String, Regex, Exception, Inner classes, Multithreading, I/O Stream, Networking, AWT, Swing, Reflection, Collection, etc.
2. Java EE (Java Enterprise Edition) is an enterprise platform which is mainly used to develop web and enterprise applications. It is built on the top of the Java SE platform. It includes topics like Servlet, JSP, Web Services, EJB, JPA, etc.
3. Java ME (Java Micro Edition) is a micro platform which is mainly used to develop mobile applications.
4. JavaFX is used to develop rich internet applications. It uses a light-weight user interface AP
JDK, JRE, and JVM
1. JVM (Java Virtual Machine) is an abstract machine. It is called a virtual machine because it doesn’t physically exist. It is a specification that provides a runtime environment in which Java byte code can be executed. It can also run those programs which are written in other languages and compiled to Java byte code. JVMs are available for many hardware and software platforms.
2. JRE is an acronym for Java Runtime Environment. It is also written as Java RTE. The Java Runtime Environment is a set of software tools which are used for developing Java applications. It is used to provide the runtime environment. It is the implementation of JVM. It physically exists. It contains a set of libraries + other files that JVM uses at runtime.
3. JDK is an acronym for Java Development Kit. The Java Development Kit (JDK) is a software development environment which is used to develop Java applications and applets. It physically exists. It contains JRE + development tools.
History
James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. The small team of sun engineers called Green Team.
Originally designed for small, embedded systems in electronic appliances like set-top boxes. Firstly, it was called “Greentalk” by James Gosling, and file extension was .gt
After that, it was called Oak and was developed as a part of the Green project. Why Oak? Oak is a symbol of strength and chosen as a national tree of many countries like U.S.A., France, Germany, Romania, etc.
In 1995, Oak was renamed as “Java” because it was already a trademark by Oak Technologies.