软件NetBeans IDE 7.0.1,需要单独写主类。
封装一个抽象类 Shape,其中包括有求形状面积的抽象方法getArea()和求 形状周长的非抽象方法getPerimeter()。继承该抽象类定义3个类: Triangle、Rectangle 和Circle,分别重写和重载继承方法。封装执行主类,分别创建一个Triangle、 Rectangle 和Circle 对象,将各类形状的面积和周长输出。
主类
//主类不用写这么多也行,写在它们原本类里也可以
//Shape s=new Shape();非法,抽象类是不能实例化对象的,所以双斜线不能去;
double a=4,b=5;
Triangle t=new Triangle();
t.getArea(a, b);
t.getPerimeter(a, b, b);
double getArea=t.getArea(4, 5);
double getPerimeter=t.getPerimeter(4, 5, 6);
System.out.println("三角形的面积是: "+getArea);
System.out.println("三角形的周长是: "+getPerimeter);
a=7;
b=8;
Rectangle r=new Rectangle();
r.getArea(a, b);
r.getPerimeter(a, b);
getArea=r.getArea(7, 8);
getPerimeter=r.getPerimeter(7, 8);
System.out.println("矩形的面积是: "+getArea);
System.out.println("矩形的周长是: "+getPerimeter);
a=2;
Circle c=new Circle();
c.getArea(a, b);
c.getPerimeter(a, b);
getArea=c.getArea(2,2);
getPerimeter=c.getPerimeter(2,2);
System.out.println("圆形的面积是: "+getArea);
System.out.println("圆形的周长是: "+getPerimeter);
shape类:
public abstract class Shape {
public abstract double getArea(double a,double b);
public double getPerimeter(double a,double b,double c){
return a+b+c;
}
}
Triangle类:
public class Triangle extends Shape{
private double a,b,c;
public double getArea(double a,double b){
return a*b/2;
}
public double getPerimeter(double a,double b,double c){
return a+b+c;
}
}
Rectangle类:
public class Rectangle extends Shape{
private double a,b;
public double getArea(double a,double b){
return a*b;
}
public double getPerimeter(double a,double b){
return (a+b)*2;
}
}
Circle类:
public class Circle extends Shape{
private double a,b;
public double getArea(double a,double b){
return a*a*Math.PI;
}
public double getPerimeter(double a,double b){
return 2*a*Math.PI;
}
}