double radius
public Circle(double rad) {
radius = rad
}
public double calcArea() {
return Math.PI * radius * radius
}
public static void main(String[] args) {
Circle c = new Circle(3)
System.out.println(c.calcArea())
}
}
代码如下：
import java.util.Scannerclass Circle {
private double radius
public Circle(double radius) {
this.radius = radius
}
public double getRadius() {
return radius
}
public void setRadius(double radius) {
this.radius = radius
}
public double getArea() {
return Math.PI * radius * radius
}
public double getPerimeter() {
return 2 * Math.PI * radius
}
}
public class App {
public static void main(String[] argv) {
Scanner scanner = new Scanner(System.in)
System.out.print("请输入圆半径：")
double r = scanner.nextDouble()
Circle c = new Circle(r)
System.out.println("面积：" + c.getArea() + "，周长：" + c.getPerimeter())
}
}
运行结果：
public class CircleTest {public static void main(String[] args) {
double radius = 10
Circle circle = new Circle()
circle.setRadius(radius)
System.out.println("半径" + radius + "的圆,周长: " + circle.perimeter() + ", 面积: " + circle.area())
double radius2 = 11
Circle circle2 = new Circle(radius2)
System.out.println("半径" + radius2 + "的圆,周长: " + circle2.perimeter() + ", 面积: " + circle2.area())
}
}
class Circle {
private double radius
public Circle() {
}
public Circle(double radius) {
this.radius = radius
}
public double area() {
return Math.PI * Math.pow(this.radius, 2)
}
public double perimeter() {
return Math.PI * this.radius * 2
}
public double getRadius() {
return radius
}
public void setRadius(double radius) {
this.radius = radius
}
}
