1 public class L1106 {
2
3 public static void main(String[] args) {
4 // TODO Auto-generated method stub
5 TestDemo circle1 = new TestDemo();
6 double area=circle1.getArea();
7 System.out.println(area);
8 TestDemo circle2=new TestDemo(10);
9 System.out.println(circle2.getArea());
10 System.out.println(circle1.getPerimeter());
11 System.out.println(circle2.getPerimeter());
12 double ridius=10;
13 double areaCircle=Math.PI*ridius*ridius;
14 System.out.println(areaCircle);
15 circle2.setRadius(5);
16 System.out.println(circle2.getArea());
17 }
18
19 }
20
21
22
23
24 public class TestDemo {
25
26 private double radius;
27
28 public TestDemo(double radius) {
29 this.radius = radius;
30 }
31 public TestDemo() {
32 this.radius = 1.0;
33 }
34 public double getArea() {
35 return Math.PI * radius * radius;
36 }
37 public double getPerimeter() {
38 return 2 * Math.PI * radius;
39 }
40 public void setRadius(double newRadius) {
41 this.radius = newRadius;
42 }
43 }
