java打印菱形，空心菱形

import java.util.*;
public class rhombus {
	void hollow(int s) {  //打印空心菱形
		int i,k; 
		for (k = 0; k < s ; k++ ){
			for (i = 0; i < s-k-1 ;i++ ){
			System.out.print(" ");   
			}
			for (i = 0; i <= k; i++ ) {
				if (i == 0 || i == k){
					System.out.print("* ");
				}
				else
					System.out.print("  ");		
		    }
			System.out.println();
		}
		for (k = 0; k < s-1; k ++ ){
			for (i = 0; i <= k ; i++ ){
				System.out.print(" ");
			}
			for (i = 0; i < s-k-1 ;i++ )	{
				if (i == 0 || i == s-k-2)	{
					System.out.print("* ");
				}
				else
					System.out.print("  ");		
			}
			System.out.println();
		}		
	}
	 void solid(int s) { // 打印實心菱形
		int i,k;
		for (k = 0; k < s ; k++ )	{
			for (i = 0; i < s-k-1 ;i++ )
		   {
			System.out.print(" ");
		    }
		    for (i = 0; i <= k; i++ )
		   {
			System.out.print("* ");
		    }
			System.out.println();
		}
		
		for (k = 0; k < s; k ++ )
		{
			for (i = 0; i <= k ; i++ )
			{
				System.out.print(" ");
			}
			for (i = 0; i < s-k-1 ;i++ )
			{
				System.out.print("* ");
			}
			System.out.println();
		}
		
	}
	public static void main(String[] args)
	{
		System.out.println("請輸入一個數:");
		Scanner cin = new Scanner(System.in);
		int num = cin.nextInt();
		rhombus rb = new rhombus();

		rb.hollow(num);
		System.out.println();
		rb.solid(num);	
	}
}