Shansi Valley P290 polymorphism exercise

package p290;

class Base{
    
	int  count = 10;
	public void display(){
    
		System.out.println(this.count);
	}
}

class Sub extends Base{
    
	int count = 20;
	public void display(){
    
		System.out.println(this.count);
	}
}
public class FieldMethodTest {
    
	public static void main(String[] args){
    
		Sub s = new Sub();
		System.out.println(s.count);		//20
		s.display();		//20
		Base b = s;		// polymorphism 
		// Reference data type , The comparison is whether the address values are the same 
		System.out.println(b == s);		//true
		System.out.println(b.count);		//10
		// Call subclass overridden methods 
		b.display();			//20
		
		
	}

}