代码:
package Circle;
import static java.lang.Math.PI;
public class Homework01 {
	public static void main(String[] args){
	Circle cc = new Circle(1.0, 1.0);
	cc.r = 10.0;
	cc.circleArea();
    }
}
class Circle{
	double x, y;
	double r;
	
	public Circle(double x, double y){
	this.x = x;
	this.y = y;
	System.out.printf("圆点坐标为(%f, %f)\n", x, y);
	}
	//System.out.printf("圆点坐标为(%f, %f)\n", x, y);
	void circleArea(){
	System.out.println("圆的面积为: " + (PI * r * r));
	}
}
问题:请问在类中为什么将红色打印语句写外面就是错的?是类中只能由函数中来完成打印吗?