public class PaintRound{    /**     * @author Dream_e.     * @version  v1.0     */    private int r;//圆的半径    PaintRound(int r){        this.r = r;    }    public void paint(){        int y = 2*r;//y的最大值为半径的2倍        int x = 0;        int c = 0;        int z = 2;//坐标轴递减量.        for(int j = y; j >= 0; j-=z){            x = getX(r,y);            System.out.print(getSpace(x)+"*");            c = (r-x)*2;            System.out.println(getSpace(c)+"*");            y-=z;        }    }    //计算X坐标.    private int getX(int r, int y){        double temp = Math.sqrt(r*r-(r-y)*(r-y));//根据圆内的正角三角形计算出圆上某点到圆心的X轴距离        int x = (int)Math.round(r-temp);        return x;    }    //计算要打印的空格数量.    private String getSpace(int c){        String space = " ";        for(int i = 0; i < c; i++){            space += " ";        }        return space;    }    public static void main(String[] args){        new PaintRound(10).paint();    }}