Model answers for test 5

Q1: just run the code

Q2:

part a:

abstract class HorizontalScrollbarAdapter extends Scrollbar 
    implements AdjustmentListener {

    public HorizontalScrollbarAdapter() {
	super(Scrollbar.HORIZONTAL);
	addAdjustmentListener(this);
    }

    public HorizontalScrollbarAdapter(int v, int s, int min, int max) {
	super(Scrollbar.HORIZONTAL,v,s,min,max);
	addAdjustmentListener(this);
    }

    public void adjustmentValueChanged(AdjustmentEvent e) {
	setFromBar();
    }

    abstract public void setFromBar();

}

part b:

p.add(new HorizontalScrollbarAdapter(0,60,0,300) {
	public void setFromBar() {sValue = getValue();}
    });


Q3:
// accept whatever CORRECT hash function,
// even silly stuff like: public int hashCode() { return 0;}
// correctness matters
// 
// THIS IS WRONG:
//
// public int hashCode() { return super.hashCode();}
//
// why?

public class PointXY {

    private int x;
    private int y;

    public int getX() { return x;}
    public int getY() { return y;}

    public PointXY() {x=0;y=0;}

    public PointXY(int x1, int y1) {x=x1;y=y1;}

    public int hashCode() { return (17 + x)*43 + y;}

    public boolean equals(Object o) {

	if (o == this) return true;
	if (o == null) return false;
	if (getClass() != o.getClass()) return false;
	PointXY o1 = (PointXY) o;
	return (x == o1.x) && (y == o1.y);
    }
}



import java.awt.*;

public class ColorPointXY extends PointXY {

    private Color color;

    public Color getColor() { return color;}
    public void setColor(Color c) { color = c;}

    public ColorPointXY() {color = Color.red;}

    public ColorPointXY(Color c) {color = c;}

    public ColorPointXY(Color c, int x, int y) {
	super(x,y);
	color = c;
    }

    public int hashCode() { 
	return (23 + super.hashCode())*43 + color.hashCode();
    }

    public boolean equals(Object o) {

	if (o == this) return true;
	if (o == null) return false;
	if (getClass() != o.getClass()) return false;
	ColorPointXY o1 = (ColorPointXY) o;
	return color.equals(o1.color) && super.equals(o1);
    }
}