how to use a variable from a superclass to a subclass?

Question

I have a superclass and I want to use a variable that is inside this superclass into my subclass. How can this be possible?

Answer 1

Just make the field protected, meaning that it should be visible to all derived classes.

Answer 2

I have a superclass and I want to use a variable that is inside this superclass into my subclass. How can this be possible?

If your variable is declared as protected or public (or) your variable hasdefault access privileges(in which case you don't specify with any keyword) and they are in same package(--> You can access it in the subclass directly. You may use this keyword if you are specific.

Example:

   public class A{
         protected int field=1;
   } 
   public class B extends A{
         public B(){
             System.out.println(this.field);
         }
         public static void main(String args[]){
           new B();
        }
   }

Please note that variable-overriding is not possible. If you have a variable with the same name as in super class then you are out of luck to directly access it. Then you may use super keyword.

       public class A{
             protected int field=1;
       } 
       public class B extends A{
             protected int field=3;
             public B(){
                 System.out.println(this.field);
                 System.out.println(super.field);
             }
        public static void main(String args[]){
           new B();
        }
       }