Using Multiple Classes

Huh!! Like a math class isn't it? Ah I don't worry it's over for a while. Let's go for the classes and methods...

• What's a Java Class?

A class is nothing but a blueprint or a template for creating different objects which defines its properties and behaviors. Java class objects exhibit the properties and behaviors defined by its class. A class can contain fields and methods to describe the behavior of an object.

• What's a Java Method?

A Java method is a collection of statements that are grouped together to perform an operation. When you call the System.out.println() method, for example, the system actually executes several statements in order to display a message on the console.

I hope you guys got at least a little bit of idea about these Classes & Methods.

• Create another class. right click project >> New >> Class

• You can name the class by any name. But for now use "sub_clz"

• in the sub_clz...

public class sub_clz {

public void sampleMsg(){

System.out.println("This Message from another CLASS");

}

}

In this class we created method [ "public void sampleMsg(){" ] . Inside that method we print [ "This Message from another CLASS" ] message.

• now run the code
• Nothing will happen, now go to the main class(used before)
• Inside the main class we have the main method ( public static void main(String []args) )
• Only things inside this main method will compile. And also the there must be only one main method.

Calling another class

•  Now you're in the main method. You have to call the "sub_clz". Simple.... 

                  [  classname objectname = new classname ]  (template)

• OK we called the sub_clz.
• Next we're gonna call the method inside the sub_clz.  [ "public void sampleMsg(){" ]
• This how we do that.

                               [   objectname.method(); ]    (template)

Much more to come, before go for them if you have a problem about Objects just visit
https://docs.oracle.com/javase/tutorial/java/concepts/object.html.