继承

题目：

  定义一个图形类及其子类（三角形类和矩形类），分别计算其面积和周长。

程序：

package akko;
//图形类
class Graphical {//父类
public double width;//成员变量
public double length;
public double area;
public double Perimeter;
public double areaGraphical() {//成员方法
return area;
}
public double PerimeterGraphical() {
return Perimeter;
}
}
class rectangle extends Graphical {//子类继承父类
public double areaGraphical() {
area = width * length;
return area;
}
public double PerimeterGraphical() {
Perimeter = (width + length) * 2;
return Perimeter;
}
}
class Triangle extends Graphical {//子类继承父类
public double high;
public double bottom;
public double side;
public double areaGraphical() {
area = (bottom * high) / 2;
return area;
}
public double PerimeterGraphical() {
Perimeter = high + bottom + side;
return Perimeter;
}
}
public class Main {//主类
public static void main(String[] args) {
rectangle p1 = new rectangle();// 声明对象和创建对象
p1.width = 5;
p1.length = 7;
p1.areaGraphical();
p1.PerimeterGraphical();
System.out.println("矩形面积:" + p1.areaGraphical() + "矩形周长:" + p1.PerimeterGraphical());//输出
Triangle p2 = new Triangle();// 声明对象和创建对象
p2.high = 8;
p2.side = 9;
p2.bottom = 13;
p2.areaGraphical();
p2.PerimeterGraphical();
System.out.println("三角形面积:" + p2.areaGraphical() + "三角形周长:" + p2.PerimeterGraphical());//输出
//自动生成的方法存根
}
}