打印出如下图案（菱形）

import java.util.Scanner;

public class LingXing {
    public static void main(String[] args){
        int a;
        int b;
        System.out.println("请输入：");
        Scanner in = new Scanner(System.in);
        b = in.nextInt();
        a = (b+1)/2;
        for(int i = 0;i<a;i++){
            for(int k = a-1;k>i;k--){
                System.out.println(" ");
            }
            for(int j = 0;j<2*i+1;j++){
                System.out.println("*");
            }
            System.out.println();
        }
        for(int i =1;i<=a-1;i++){
            for(int j = 1;j<=i;j++){
                System.out.println(" ");
            }
            for(int k = 2*a-3;k>=2*i-1;k--){
                System.out.println("*");
            }
            System.out.println();
        }
    }
}