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  • 计算几何图形的面积

    Shape:

    Shape:

    package Area;
    /**
     * 求面積
     * @author Administrator
     *
     */
    public abstract class Shape {
    public String getName(){
        return this.getClass().getName();//獲得類名稱
    }
    public abstract double getArea();
    
    }
    View Code

    Circle:

    package Area;
    
    public class Circle extends Shape{
    private double radius;
    public Circle(){
    }
    public Circle(double radius){
        this.radius=radius;
    }
    public double getArea(){//主要是抽象的實現
        return Math.PI*Math.pow(radius,2);
    }
    }
    View Code

    Triangle:

    package Area;
    
    public class Triangle extends Shape{
    private double x;
    private double y;
    public Triangle(){
        
    }
    public double getArea(){
        return (x*y)/2;
    }
    public Triangle(double x,double y){
        this.x=x;
        this.y=y;
    }
    }
    View Code

    Test:

    package Area;
    
    public class Test {
    
        public static void main(String[] args) {
            // TODO Auto-generated method stub
            Circle circle = new Circle(1);
            System.out.println("the shape is:" + circle.getName());
            System.out.println("the Area: "+circle.getArea());
            
            Shape tri=new Triangle(1,1);
            System.out.println("the shape is:" +tri.getName());
            System.out.println("the shape is:" + tri.getArea());
        }
    
    }
    View Code

     focus :

    在抽象类中,可以定义抽象方法,用abstrat修饰,包含抽象方法的类一定是抽象类,而抽象类不一定包含抽象方法

    抽象类是不能直接被实例化的,如果要获得该类的实例,可以使用静态方法传剪其类对象,

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  • 原文地址:https://www.cnblogs.com/helloworld2019/p/10626745.html
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