demoboxweight.java

it is a good tool to help you study java

class Box{
double width;
double heigth;
double depth;
Box(Box ob){
width=ob.width;
heigth=ob.heigth;
depth=ob.depth;
}
Box(double w,double h,double d){
width=w;
heigth=h;
depth=d;
}
Box(){
width=-1;
heigth=-1;
depth=-1;
}
Box(double len){
width=depth=heigth=len;
}
double vulume(){

return width*depth*depth;
}}
class BoxWeight extends Box{
double weight;
BoxWeight(double w,double h,double d,double m){
width=w;
heigth=h;
depth=d;
weight=m;
}
}
class DemoBoxWeight{
public static void main(String args[]){
BoxWeight mybox1=new BoxWeight(10,20,15,34.3);
BoxWeight mybox2=new BoxWeight(2,3,4,0.076);
double vol;
vol=mybox1.vulume();
System.out.println("volume of mybox1 is:"+vol);
System.out.println("wight of mybox1 is:"+mybox1.weight);
System.out.println();
vol=mybox2.vulume();
System.out.println("volume of mybox2 is:"+vol);
System.out.println("wight of mybox2 is:"+mybox2.weight);

}
}
//可以用超类定义的任何形式的构造函数,调用super(),执行的构造函数将是与所//传的参数项匹配的那个.