Java is a programming language developed by Sun Microsystems, the company in which Canadian IT programmer James Gosling was a developer who developed the Java programming language in 1995.
in the year 1991, James Gosling and his Team start a project. Their Team name was Green Team and from here Java history began.
Inital name of the java is green talk with file .gt extension, further rename to OAK. Because OAK is the national tree of many countries (USA, FRANCE etc.) also there is a company registered with OAK name. So they start searching a unique name which does not exist and one day when they are in Indonesia island they ordered coffee a coffee got an idea to rename OAK to Java So, he discussed with their team member and they also like this name So, later renamed to Java with coffee symbol.
The first version of java (JDK1.0) was released on 23 January, 1996.
java is a class based high level programming languge. at starting java programming mainly used for electronic devices(Remote, Setbox, Television) etc. James Gosling want to develop a remote system with which they want to control the device from a single remote.
Latter java has also become popular in the Internet Programming as well. Now a days Java is used to develop Desktop, Web and Mobile applications.
A predefined Java class always starts with a capital letter.
Purpose to develop Java Programming Language
Simple answer WORA(Write Once Run Anywhere).
Flavours of Java
According to the SunMicroSystem java is available in 3 flavors
- 1. Standard Edition
- It is used to develop Standalone applications. It is also known as J2SE,JSE.
-
Example:Core Java(JSE) mainly used for SOFTWARE.
- 2. Enterprise Edition
- It is used to develop web applications. It is also known as J2EE,JEE. Advanced Java(JEE) mainly used for web apps.
-
Advanced Java (JEE) mainly used for WEB
- 3. Micro Edition
- Macro edition which is used for developing device programs and mobile applications It is also known as J2ME,JME
-
Android Java(JME) mainly used for mobiles APP.
Java layers
Java works on 3 basic important layers
- 1. Presentation layer(controller)
- First point of contact.
-
Example: user interface of the application that presents the application’s features and data to the user.
- 2. Service layer(main work)
- This layer contains the business logic that drives the application’s core functionalities
-
Application’s core functionalities: Like making decisions, calculations, evaluations, and processing the data passing between the other two layers.
- 3. data access layer(DAO/Repository layer)
- This layer is responsible for interacting with databases to save and restore application data.
-
databases.
JDK
JDK stands for Java Development Kit provide all the tools to work with java language. inside JDK contains JRE and JVM.
JRE: JRE stands for Java Runtime Envirnment. it provide an envirnment to execute the Java program. it is a kind of compiler and check program sytntax.
it internally contains JVM .
JVM: JVM stands for Java Virtual Machine, it is a software in the form of interpreter written in C language It is used to execute Java program. It basically works after the compiler generates a .class file, then JVM interprete .class file to execute Java program.
Java Program complete execution process
java program always begin with the main function.
execution is done in two steps
Compilation process
Execution process in Detail
Why public static void main(String args[ ])
Rules:
Save:
class_name.java
Compilation:
javac class_name.java
Execution/Run:
java class_name
Features of Java
Frequently Asked Questions
- Simple and easy to learn .
- Open source .
- Plateform independent .
- Secure .
- Embeded .
- Compiled and intrepreted .
- Roboust .
- Large library and framworks .