Basics & Hello World Program (Part 1)
When we consider a Java program, it can be defined as a collection of objects that communicate with 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.
Note 🔔
As you have installed ECLIPSE IDE in your system , you are now ready to dive into the ocean of Java.
Steps to open a new file:-
1. Go to File > New > Java Project > (Give your project a name) > (Project is created)
2. Open your Project > Right click on your project > New > Class
3. Give your class name (name of class should start with a capital letter eg:- Class MyFirstJavaProgram)
4. Your class is where your main body of code resides.
To Run & Save Program:-
After writing your code have a habit of saving of project from time to time by pressing Ctrl + S
To Run , At header bar you will see a green play type button , play that and output will be generated.
Let us look at a simple code that will print the words Hello World.
public class MyClass {
public static void main(String []args) {
System.out.println("Hello World");
}
} Output:-
Hello World