编程题：空心菱形

import java.util.Scanner;
public class Demo {
    public static void main(String[] args) {
        Scanner src=new Scanner(System.in);
        System.out.println("你想要输出几行空心菱形？");
        Integer size=src.nextInt();
        if (size % 2==0){
            size++;
        }
        //上半部分
        for (int i = 0; i<size/2+1; i++) {
            for (int j =size/2+1;j>i+1 ; j--) {
                System.out.print(" ");
            }
            for (int j = 0; j <2*i+1; j++) {
                if (j==0||j==i*2)
                {
                    System.out.print("*");
                }else{
                    System.out.print(" ");
                }
            }
            System.out.println();
        }
        //下半部分
        for (int j=size/2+1; j<size; j++) {
            for (int k =0;k<j-size/2; k++) {
                System.out.print(" ");
            }
            for (int i = 0; i <size*2-j*2-1; i++) {
                if(i==0||i==2*(size-j-1)){
                    System.out.print("*");
                }else{
                    System.out.print(" ");
                }
            }
            System.out.println();
        }
    }
}