Java Basics

Basics of Java
James Gosling
     Java is one of the high level object oriented programming language or technology used for developing dynamic web applications. Java language developed at SUN Micro Systems in the year 1995 under the guidance of James Gosling and there team. Originally SUN Micro Systems is one of the Academic university (Standford University Network)
Whatever the software developed in the year 1990, SUN Micro Systems has released on the name of oak, which is original name of java (scientifically oak is one of the tree name). The OAK has taken 18 months to develop.
The oak is unable to fulfill all requirements of the industry. So James Gosling again reviews this oak and released with the name of java in the year 1995. Scientifically java is one of the coffee seed name.
Java divided into three categories, they are
  • ·         J2SE (Java 2 Standard Edition)
  •           J2EE (Java 2 Enterprise Edition)
  •        J2ME (Java 2 Micro or Mobile Edition)

J2SE ( Java Standard Edition)
J2SE is used for developing client side applications.
J2EE ( Java Enterprise Edition)
J2EE is used for developing server side applications.
J2ME ( Java Micro/Mobile Edition)

J2ME is used for developing mobile or wireless application by making use of a predefined protocol called WAP(wireless Access / Application protocol).

Java Version History

The following java versions that has been released. Current stable release of Java is Java SE 8.
  1. JDK Alpha and Beta (1995)
  2. JDK 1.0 (23rd Jan, 1996)
  3. JDK 1.1 (19th Feb, 1997)
  4. J2SE 1.2 (8th Dec, 1998)
  5. J2SE 1.3 (8th May, 2000)
  6. J2SE 1.4 (6th Feb, 2002)
  7. J2SE 5.0 (30th Sep, 2004)
  8. Java SE 6 (11th Dec, 2006)
  9. Java SE 7 (28th July, 2011)
  10. Java SE 8 (18th March, 2014)

Structure of Java Program
     Structure of a java program is the standard format released by Language developer to the Industry programmer.
  Sun Micro System has prescribed the following structure for the java programmers for developing java application.

         package is a collection of classes, interfaces and sub-packages. A sub package contains collection of classes, interfaces and sub-sub packages etc. java.lang.*; package is imported by default and this package is known as default package.
  • Class is keyword used for developing user defined data type and every java program must start with a concept of class.
  • "ClassName" represent a java valid variable name treated as a name of the class each and every class name in java is treated as user-defined data type.
  • Data member represents either instance or static they will be selected based on the name of the class.
  • User-defined methods represents either instance or static they are meant for performing the operations either once or each and every time.
  • Each and every java program starts execution from the main() method. And hence main() method is known as program driver.
  • Since main() method of java is not returning any value and hence its return type must be void.
  • Since main() method of java executes only once throughout the java program execution and hence its nature must be static.
  • Since main() method must be accessed by every java programmer and hence whose access specifier must be public.
  • Each and every main() method of java must take array of objects of String.
  • Block of statements represents set of executable statements which are in term calling user-defined methods are containing business-logic.
  • The file naming conversion in the java programming is that which-ever class is containing main() method, that class name must be given as a file name with an extension .java.

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