JAVA学习日记29-0803

今天学了什么

以点类和圆类设计球类

点类：

package sphere;

public class Point {
protected double x,y;
public Point(double x,double y){
this.x=x;
this.y=y;
}
public void setx(double x) {
this.x=x;
}
public void sety(double y) {
this.y=y;
}
public double getx() {
return x;
}
public double gety() {
return y;
}
}

圆类：

package sphere;

public class Circle extends Point {
final double PI=3.14;
protected double radius;
public Circle(double x,double y,double radius) {
super(x,y);
this.radius=radius;
}
public void setr(double r) {
this.radius=r;
}
public double getr() {
return radius;
}
public double area() {
return PI*radius*radius;
}
}

球类：

package sphere;

import cylinder.Circle;

public class Sphere extends Circle {

public Sphere(double x, double y, double radius) {
super(x, y, radius);
}
public double sarea() {
return 4*area();
}
public double volume() {
return (4*PI*radius*radius*radius) / 3;
}

public static void main(String[] args) {
Sphere s = new Sphere(0, 0, 0);
s.setx(1);
s.sety(1);
s.setr(2);
System.out.println("("+s.x+","+s.y+")"+" radius="+s.radius+" area="+s.area());
System.out.println("sarea="+s.sarea()+" volume="+s.volume());
}

}

运行截图：

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