Java Learning 1

a Java class

Attafottty of aclass

When thejVM starts running, it looks for the class you give it at the com-

mand line. Then it starts looking for a specially-Written method that looks

exactly like:

public static void main (String() argsl {

// your code goes here

}

Next, theJVM runs everything between the curly braces { }of your main

method. EveryJava application has to have at least one class. and at least

one main method (not one main per class , just one main per application).

Writing a class with main

In Java, everything goes in a class. You'll type your source code file (with a

.java extension), then compile it into a new class file (with a . class extension).

When you run your program, you're really running a class.

Running a program means telling the Java VIrtual Machine (JVM) to "Load the

Hello class, then start executing its main () method. Keep running 'til all the

code in main is finished."

What can you say in the main method ???

Your code can tell the JVM to :

1. Statements : declarations , assignments , method calls

int x  =3;

String name = "Dirk";

x = x * 17;

System .out .print("x is " + x);

double d = Math.random();

// this is a comment

2. Loops : for , while , do while

 while(x < 10)

{

System.out.println("Java");

}

3.Branching : if , else . else if