Need help with Instance Variable and fields

[Joe Simpson]

Ok. I am completely lost when it comes to the difference between instance variable(non-static fields) and class variables(static fields)? I have looked and researched for the past couple of hours and for some reason I can not figure out what instance really even means in this context? I am just completely lost when it comes to this. Can someone I guess dumb it down for me? Thanks.

[Junilu Lacar]

Have you experimented with some small programs? That's one of the best ways to understand.

public class Experiment {
    public static void main(String[] args) {

         System.out.println(Person.instancesCreated);

         Person adam = new Person("Adam");
         System.out.println(Person.instancesCreated);

         Person eve = new Person("Eve");
         System.out.println(Person.instancesCreated);

         System.out.println(adam.name);
         System.out.println(eve.name);

         Person.common = "Something";
         System.out.println(Person.common);
         System.out.println(adam.common);
         System.out.println(eve.common);

         eve.common = "Another thing";

         System.out.println(Person.common);
         System.out.println(adam.common);
         System.out.println(eve.common);
     }
}

class Person {
    static String common;
    static int instancesCreated;
 
    String name;

    Person(String name) {
        instancesCreated++;
        this.name = name;
    }
}

The references to the static variable common through instances on lines 17, 18, 20, 23, 24 is not good practice but it demonstrates the behavior of static variables. Basically, static or class variables are shared by all instances. Instance variables are specific to each object/instance.

[Tim Brelsford]

This video will help
https://www.youtube.com/watch?v=T8dNBmK40d0