public static void main(String[] args) {
Shape s1=new Rectangle();
System.out.println("矩形的周长是:"+s1.calPerimeter());
System.out.println("矩形的面积是:"+s1.calArea());
Shape s2=new Circle();
System.out.println("圆的周长是:"+s2.calPerimeter());
System.out.println("圆的面积是:"+s2.calArea());
}
Shape s1=new Rectangle();
System.out.println("矩形的周长是:"+s1.calPerimeter());
System.out.println("矩形的面积是:"+s1.calArea());
Shape s2=new Circle();
System.out.println("圆的周长是:"+s2.calPerimeter());
System.out.println("圆的面积是:"+s2.calArea());
}
2017-05-26
/**
* 圆形
* @author Administrator
*
*/
public class Circle extends Shape {
public double calPerimeter() {
return 2*pi*radius;
}
public double calArea() {
return pi*radius*radius;
}
}
* 圆形
* @author Administrator
*
*/
public class Circle extends Shape {
public double calPerimeter() {
return 2*pi*radius;
}
public double calArea() {
return pi*radius*radius;
}
}
2017-05-26
/**
* 长方形
* @author Administrator
*
*/
public class Rectangle extends Shape {
public double calPerimeter() {
return (length+wide)*2;
}
public double calArea() {
return length*wide;
}
}
* 长方形
* @author Administrator
*
*/
public class Rectangle extends Shape {
public double calPerimeter() {
return (length+wide)*2;
}
public double calArea() {
return length*wide;
}
}
2017-05-26
public abstract class Shape {
double length=3.0;//长度
double wide=4.0;//宽度
double radius=5.0;//半径
double pi=3.14;
public abstract double calPerimeter();//计算图形周长
public abstract double calArea();//计算面积
}
double length=3.0;//长度
double wide=4.0;//宽度
double radius=5.0;//半径
double pi=3.14;
public abstract double calPerimeter();//计算图形周长
public abstract double calArea();//计算面积
}
2017-05-26
已采纳回答 / Justeasy
tostring方法是object类里的方法,主要返回哈希码,视频的dog类重写了Object类的tostring方法(继承关系),作者这样做为了说明继承关系与用途,求采纳,谢谢
2017-05-26
最赞回答 / 慕粉1437489196
构造方法前面是没有任何返回符,不能加任何返回类型,包括void.一个构造方法一旦加了void,那么这个就不是构造方法了,变成了一个普通的方法。
2017-05-26