java 第五週實驗【報告3】

3.封裝一類圓形對象Circle，該類對象具有半徑的屬性，具有初始化圓的功能、修改半徑的功能、求周長的功能、求面積的功能。package hu;

public class TestCircle {

private double r;

TestCircle(double r){
this.r = r;
}
TestCircle(){
this.r = 1;
}
public void set_r(double r){
this.r  = r;
}

public double get_Perimeter(){
double s=2*Math.PI*r;
return s;
}
public double get_Area(){
double s1;
s1=(Math.PI)*r*r;
return s1;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
TestCircle t = new TestCircle(3);
t.get_Area();
t.get_Perimeter();
        double x1,x2;
        x1=t.get_Area();
        x2=t.get_Perimeter();
        System.out.println(x1+"    "+x2);

}

}