Java 多态性的使用

 1 package com.bytezreo.duotai3;
 2
 3 /***
 4  *
 5  * @Description  练习多态性的使用
 6  * @author  Bytezero·zhenglei!      Email:420498246@qq.com
 7  * @version
 8  * @date 2021年9月24日上午8:46:24
 9  * @
10  * 编写 equalsArea 方法测试两个对象的面积是否相等（注意方法的参数类型，利用动态绑定技术）
11  * 编写 displayGeometricObject方法显示对象的面积（注意方法的参数类型，利用动态绑定技术）
12  *
13  *
14  */
15 public class GeometricTest
16 {
17     public static void main(String[] args)
18     {
19         GeometricTest test = new GeometricTest();
20
21         Circle c1 = new Circle(2.3,"black",5.0);
22         test.displayGeometricObject(c1);
23
24         Circle c2 = new Circle(4.3,"red",5.0);
25         test.displayGeometricObject(c2);
26          boolean isEquals = test.equalsArea(c1, c2);
27          System.out.println("c1和c2的面积是否相等：" + isEquals);
28
29         Circle c3 = new Circle(2.3,"black",5.0);
30         test.displayGeometricObject(c3);
31
32         boolean isEquals1 = test.equalsArea(c1, c3);
33         System.out.println("c1和c3的面积是否相等：" + isEquals1);
34
35         MyRectangle r1  = new MyRectangle(2.2,3.3,"red",1.0);
36         test.displayGeometricObject(r1);
37
38
39
40     }
41
42
43     //GeometricObject o  = new Circle(...);
44     public void displayGeometricObject(GeometricObject o)
45     {
46         System.out.println("面积为:"+ o.findAre());
47     }
48
49
50
51     //测试两个对象的面积是否相等
52     public boolean equalsArea(GeometricObject o1,GeometricObject o2)
53     {
54          return o1.findAre() == o2.findAre();
55     }
56
57
58
59
60 }

 1 package com.bytezreo.duotai3;
 2
 3 public class GeometricObject    //几何图形
 4 {
 5     protected  String color;
 6     protected  double weight;
 7     public String getColor() {
 8         return color;
 9     }
10     public void setColor(String color) {
11         this.color = color;
12     }
13     public double getWeight() {
14         return weight;
15     }
16     public void setWeight(double weight) {
17         this.weight = weight;
18     }
19 //    public GeometricObject()
20 //    {
21 //
22 //    }
23     public GeometricObject(String color, double weight) {
24         super();
25         this.color = color;
26         this.weight = weight;
27     }
28
29
30     public double findAre()
31     {
32        return 0.0;
33     }
34
35 }

 1 package com.bytezreo.duotai3;
 2
 3 public class Circle extends GeometricObject
 4 {
 5
 6     private double radius;
 7
 8     public Circle(double radius,String color, double weight)
 9     {
10         super(color, weight);
11
12         this.radius = radius;
13
14     }
15
16     public double getRadius() {
17         return radius;
18     }
19
20     public void setRadius(double radius) {
21         this.radius = radius;
22     }
23
24     @Override
25     public double findAre()
26     {
27         // TODO Auto-generated method stub
28         return 3.14 *radius *radius;
29     }
30
31
32
33
34
35
36
37
38 }

 1 package com.bytezreo.duotai3;
 2
 3 public class MyRectangle extends GeometricObject
 4 {
 5     private double width;
 6     private double height;
 7
 8     public MyRectangle( double width, double height,String color, double weight)
 9     {
10         super(color, weight);
11         this.width = width;
12         this.height = height;
13
14
15
16     }
17
18     public double getWidth() {
19         return width;
20     }
21
22     public void setWidth(double width) {
23         this.width = width;
24     }
25
26     public double getHeight() {
27         return height;
28     }
29
30     public void setHeight(double height) {
31         this.height = height;
32     }
33
34
35     @Override
36     public double findAre()
37     {
38
39         return width * height;
40     }
41
42
43
44 }