Java——图形继承Shapes（形状）计算周长，面积。

旧城等待， 2023-03-13 05:54 8阅读 0赞

abstract class Shapes {
        		//定义抽象类 Shapes
    	abstract public double area();  	//周长
    	abstract public double square();	//面积
    }
    
    class Triangle extends Shapes {
          		//继承 Shapes，定义三角型
    	private double a, b, c;
    
    	public Triangle(double a, double b, double c) {
        
    		this.a = a; 
    		this.b = b;
    		this.c = c;	
    	}
    	public double square()  {
        
    		double p = (a + b +c) / 2;
    		return Math.sqrt(p * (p - a) * (p- b) * (p- c));
    	}
    	public double area()  {
        
    		double cir = (a + b +c);
    		return cir;
    	}
    	public String toString() {
        
    		return "三角形：边长"+a+","+b+","+c;
    	}
    }
    
    class Rectangle extends Shapes {
          //定义矩形
    	private double width, height;//长，宽
    	public Rectangle(double j, double k) {
        
    		width = j; height = k;
    	}
    	public double area() {
        
    		double Rectangle =(width + height)*2;
    		return Rectangle;
    	}
    	public String toString() {
        
    		return "矩形：宽 "+width+" 高 "+height;
    	}
    	public double square() {
        
    		double Rectangle =width* height;
    		return Rectangle;
    	}
    }
    
    class Circle extends Shapes {
           //定义圆
    	private double r;
    	public Circle(double r) {
        
    		this.r = r;
    	}
    	public double area() {
        
    		return 3.14 * 2 * r;
    	}
    	public double square() {
        
    		return 3.14 * r * r;
    	}
    	public String toString() {
        
    		return "圆：半径= "+ r;
    	}   
    }

以上构造了 三角形、矩形、圆的函数，定义了 计算周长（area）面积（square）的方法。  
下面是测试类代码如下：

//测试类
    public class TestShapes {
        
    	 public static void main(String args[])  {
        
    			Shapes s[] = new Shapes[3];   
    			s[0] = new Triangle(3, 4, 5);
    			s[1] = new Rectangle(5.2,4.8);
    			s[2] = new Circle(5.2);
    			for (int k= 0; k < s.length; k ++)
    			    System.out.println(s[k]+", 面积："+s[k].square()+", 周长："+s[k].area());
    		  } 
    }