package subclass.equals;
class C1 {
	int i;
	public C1(int i) { this.i = i; }
	public boolean equals(Object thatObject) {
		if (!(thatObject instanceof C1))
			return false;
		C1 that = (C1) thatObject;
		return that.i == this.i;
	}
}
class D1 extends C1 {
	int j;
	public D1(int i, int j) { super(i); this.j = j; }
	public boolean equals(Object thatObject) {
		if (!(thatObject instanceof D1))
			return false;
		D1 that = (D1) thatObject;
		return that.i == this.i && that.j == this.j;
	}
}
class C2 {
	int i;
	public C2(int i) { this.i = i; }
	public boolean equals(Object thatObject) {
		if ((thatObject == null) || (thatObject.getClass() != this.getClass()))
			return false;
		C2 that = (C2) thatObject;
		return that.i == this.i;
	}
}
class D2 extends C2{
	int j;
	public D2(int i, int j) { super(i); this.j = j; }
	public boolean equals(Object thatObject) {
		if ((thatObject == null) || (thatObject.getClass() != this.getClass()))
			return false;
		D2 that = (D2) thatObject;
		return that.i == this.i && that.j == this.j;
	}
}
public class Main {
	public static void main(String[] args) {
		C1 x1 = new C1(27);
		C1 y1 = new D1(27,42);
		System.out.println("x1==y1? " + (x1.equals(y1) ? "true" : "false"));
		System.out.println("y1==x1? " + (y1.equals(x1) ? "true" : "false"));

		C2 x2 = new C2(27);
		C2 y2 = new D2(27,42);
		System.out.println("x2==y2? " + (x2.equals(y2) ? "true" : "false"));
		System.out.println("y2==x2? " + (y2.equals(x2) ? "true" : "false"));
	}
}