Mega Code Archive
A Superclass Variable Can Reference a Subclass Object
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class RefDemo {
public static void main(String args[]) {
BoxWeight weightbox = new BoxWeight(3, 5, 7, 8.37);
Box plainbox = new Box();
double vol;
vol = weightbox.volume();
System.out.println("Volume of weightbox is " + vol);
System.out.println("Weight of weightbox is " + weightbox.weight);
System.out.println();
plainbox = weightbox;
vol = plainbox.volume();
System.out.println("Volume of plainbox is " + vol);
}
}
class Box {
private double width;
private double height;
private double depth;
Box(Box ob) {
width = ob.width;
height = ob.height;
depth = ob.depth;
}
Box(double w, double h, double d) {
width = w;
height = h;
depth = d;
}
Box() {
width = -1;
height = -1;
depth = -1;
}
Box(double len) {
width = height = depth = len;
}
double volume() {
return width * height * depth;
}
}
class BoxWeight extends Box {
double weight;
BoxWeight(BoxWeight ob) {
super(ob);
weight = ob.weight;
}
BoxWeight(double w, double h, double d, double m) {
super(w, h, d);
weight = m;
}
BoxWeight() {
super();
weight = -1;
}
BoxWeight(double len, double m) {
super(len);
weight = m;
}
}
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