Java
- Basic Syntax
When we consider a Java program, it can be defined as a collection
of objects that communicate via invoking each other's methods. Let us now
briefly look into what do class, object, methods, and instance variables mean.
·
Object −
Objects have states and behaviors. Example: A dog has states - color, name,
breed as well as behavior such as wagging their tail, barking, eating. An
object is an instance of a class.
·
Class −
A class can be defined as a template/blueprint that describes the
behavior/state that the object of its type supports.
·
Methods −
A method is basically a behavior. A class can contain many methods. It is in
methods where the logics are written, data is manipulated and all the actions
are executed.
·
Instance
Variables − Each object has its unique set of instance variables. An
object's state is created by the values assigned to these instance variables.
public class MyFirstJavaProgram {
/*
This is my first java program.
* This will print 'Hello World' as the
output
*/
public static void main(String []args) {
System.out.println("Hello
World"); // prints Hello World
}
}
Let's
look at how to save the file, compile, and run the program. Please follow the
subsequent steps −
·
Open notepad and add the code as above.
·
Save the file as: MyFirstJavaProgram.java.
·
Open a command prompt window and go to the directory where you
saved the class. Assume it's C:\.
·
Type 'javac MyFirstJavaProgram.java' and press enter to compile
your code. If there are no errors in your code, the command prompt will take
you to the next line (Assumption : The path variable is set).
·
Now, type ' java MyFirstJavaProgram ' to run your program.
·
You will be able to see ' Hello World ' printed on the window
