通过API文档查询Math类的方法，打印出近似圆，只要给定不同半径，圆的大小就会随之发生改变...

package question;import java.util.Scanner;
import java.lang.Math;public class MathTest {/*** 未搞懂* @param args*/public static void main(String[] args) {// TODO Auto-generated method stubSystem.out.println("请输入圆的半径:");Scanner in =new Scanner(System.in);int radius = in.nextInt();//使用户能够从 System.in 中读取一个数paint(radius);	//手动输入半径5	}public static void paint(int r){int y = r*2;//y=10int x = 0;int c = 0;int z = 2;for(int j=r*2;j>=0;j=j-z){//j>=0 && j<=10 j=8,x=getX(r,y);System.out.print(getSpace(x)+"*");c=(r-x)*2;System.out.println(getSpace(c)+"*");y-=z;}}public static int getX(int r,int y){int x=y-r;//x=5double t=Math.sqrt((r*r)-(x*x));return (int)Math.round(r-t);}public static String getSpace(int i){String s = " ";for(int j=0;j