梁栋用java写的画圆算法

public class PrintCircle {

/**
* @param args
*/
public static void main(String[] args) {
int n=1000;//n越大，才能越接近圆
PrintCircle p = new PrintCircle();
for(int i=0;i<2*n;i++){
p.printPoint(n,i);
}
}

private int[] getXFromY(int y,int n)//n为半径，y<2n,返回2个x
{
if(y<=n){//上半侧
int x1=n-(int)Math.sqrt(n*n-(n-y)*(n-y));
int x2=(int)Math.sqrt(n*n-(n-y)*(n-y))+n;
return new int[]{x1,x2};
}
else if(y<=2*n){//下半侧
int x1=n-(int)Math.sqrt(n*n-(n-y)*(n-y));
int x2=(int)Math.sqrt(n*n-(n-y)*(n-y))+n;
return new int[]{x1,x2};
}
return null;
}

private void printPoint(int n,int y){//半径n,在(x,y)的位置打印一个*
int x1=getXFromY(y,n)[0];
int x2=getXFromY(y,n)[1];
for(int i=0;i<=2*n;i++){
if(i==2*n) System.out.println(“n”);
if(i==x1||i==x2) System.out.print(“*”);
else System.out.print(” “);
}
}
}