// INHERIT8: demonstrate how $super$ can help classes set instance variables
// Calling $super$ means calling a constructor in a superclass.
// But, any values that Java sets occur in the subclass.

public class inherit8 {
    public static void main(String args[]) {
	
	Data1 d1 = new Data1(1);
	System.out.println(d1.m); // Output: 1

	// Does $Data2$ "store" a value in $Data1$'s instance variable $m$?
	// Create a $Data2$ object:
	Data2 d2 = new Data2(2);

	// Now check the $Data1$ object referred to by $d1$:
	System.out.println(d1.m); // Output: 1

	// Creating a $Data1$ object does not affect the $Data2$ object.
	// $d1$ and $d2$ refer to entirely different objects!
	// When $d2$ calls $super$, the value 2 is passed to a $Data1$
	// constructor, which assigns the value 2 to instance variable
	// $m$ inside $Data2$. Why? $Data2$ inherits $m$. 
	
	// So, The value of $m$ inside the object referred by $d2$
	// should be 2:
	System.out.println(d2.m); // Output: 2

    }
}

class Data1 {
    int m;
    Data1(int m) {
	this.m = m;
    }
} // class Data1

class Data2 extends Data1 {
    Data2(int m) {
	super(m);
    }
} // class Data2

/* output:
1
1
2
*/