JAVA Hello World Samples

Java

• 1991 - James Gosling, Sun Microsystems, Inc.

• Originally a platform independent language for

programming home appliances and was called “Oak”

later renamed “Java” in 1995.

• Later (1994) used for World Wide Web applications (since byte code can be

downloaded and run without compiling it)

• Eventually used as a general-purpose programming language (for the same

reason as above plus it is object-oriented)

• Why the name “Java”? Java was then named “Java”, paying homage to the

large amounts of coffee consumed by the team.

• Now owns by Oracle

• Full-fledged application programming language

• Additional capability as a Web programming language

(currently the strength of its application base)

• A pure OO programming language

• NOT radical or especially new

• Adopts its looks from C++, and its behavior from Smalltalk

• Compiled to processor-neutral instruction set then

interpreted on each supporting platform

• Extremely fast adoption rate! (due to WWW)

Java Development Environment

1. Install the Java JDK.

The latest Java SE JDK is 9. We will use Java SE JDK 8 in this course.

2. Editing a program

• Type a Java program ( source code )

• e.g :

vi editor ( Linux )

notepad ( Windows DOS prompt )

IDE (Eclipse, IntelliJ )

• Extension : .java

3. Compiling a Java program

     • The java compiler (javac) compiles java code to an

intermediate language called Java Byte Code. This is a

platform neutral low level language which can be translated

to machine code. Compiled java programs are stored in files

with the extension .class

4. Running a Java Program

   • The java interpreter is used to run a compiled program on

your computer. Each platform has its own Java Virtual

Machine which translates Java Bytecode to machine code.

/* First Java Program

*/

public class HelloWorld {

public static void main(String args[]) {

System.out.println("Hello World !");

}

}

Sample Programs