打印菱形源码

import java.io.*; public class PrintStar { static void print(int layer) { for (int i = 1; i < 2 * layer; i++) { for (int j = 1; j < 2 * layer; j++) System.out.print(shouldBeStar(i, j, layer)? "*": " "); System.out.println(); } } static boolean shouldBeStar(int i, int j, int layer) { int m = layer - Math.abs(layer - i); return j > layer - m && j < layer + m &&((i + j + layer) & 1)== 1; } public static void main(String [] args) throws java.io.IOException { int n=0; String s=null; System.out.print("请输入菱形宽度(num)："); BufferedReader sum=new BufferedReader(new InputStreamReader(System.in));//可以读入你输入的数 s=sum.readLine();//读入一行 if(s==null || s.equals(""))s="0"; n=Integer.parseInt(s); s=null; if(n>0){ System.out.println("打印宽度为"+n+"的菱形..."); print(n); } } }