1.图形类
package com.yfs.javase;
public class Shape {
//计算面积方法
public double getArea() {
System.out.println("计算面积");
return 0;
}
}
2.圆
package com.yfs.javase;
public class Circle extends Shape {
private double r;
public Circle(double r) {
this.r = r;
System.out.println("创建圆形面积");
}
public double getArea() {//覆盖父类的方法
System.out.println("计算圆形面积...");
return 3.14 * r * r;
}
}
3.矩形
package com.yfs.javase;
public class Rangton extends Shape {
private double width;
private double length;
public Rangton(double width, double length) {
this.width = width;
this.length = length;
System.out.println("创建矩形面积");
}
public double getArea() {
System.out.println("计算矩形面积...");
return width * length;
}
}
4.三角形
package com.yfs.javase;
public class Trantangle extends Shape {
private double height;
private double width;
public Trantangle(double height, double width) {
this.height = height;
this.width = width;
System.out.println("创建三角形面积");
}
public double getArea() {
System.out.println("计算三角形面积...");
return 1.0 / 2 * width * height;
}
}
5.测试
package com.yfs.javase;
import java.util.Random;
public class Test1 {
/**
* 编写一个图形类，提供计算面积的方法。
* 通过继承图形类，封装三角形，圆形，正方形类，
* 覆盖父类的方法。在测试类里随机产生10个图形，
* 面积求和。
*/
public static void main(String[] args) {
Shape[] shapes = new Shape[10];//存放子类对象
Random ran = new Random();
double sum = 0;
//创建随即图形
for (int i = 0; i < shapes.length; i++) {
int r = ran.nextInt(101);
if(r > 65) {
shapes[i] = new Circle(ran.nextInt(10));
} else if( r > 35 ){
shapes[i] = new Rangton(ran.nextInt(10),ran.nextInt(10));
//shapes[i].setWidth();
} else {
shapes[i] = new Trantangle(ran.nextInt(10), ran.nextInt(10));
}
}
System.out.println("================");
//计算随机图形面积
for (int i = 0; i < shapes.length; i++) {
// Circle c = (Circle)shapes[i];
// sum += c.getArea();
sum += shapes[i].getArea();//子类对象计算面积
}
System.out.println("sum = " + sum);
}
}