无法使我的钻石侧面对称

Question

I'm trying to make a diamond out of /,\\, and astricks only using for loops and if's but the sides come out wrong, the right side is too big and the left side is too short. this is for school by the way

public class Main
{
  public static void main (String[]args)
  {
   int n = 7;
    {
      for (int i = 0; i < n; i++)
        {
         for (int a = 0; a < (n - (i + 1)); a++)
         {
          System.out.print (" ");
         }

         for (int b = 0; b < (i * 2); b++)
         {
         if (b < n / 2)
         {
           System.out.print ("/");
         }
         else if (b == n / 2)
         {
           System.out.print ("*");
         }
           else if (b > n / 2)
         {
           System.out.print ("\\");
         }
       }
       System.out.println ();
     }

        for (int i = n - 1; i >= 0; i--)
        {
          for (int a = 0; a < (n - (i + 1)); a++)
         {
           System.out.print (" ");
         }

        for (int b = 0; b < (i * 2); b++)
        {
          if (b < n / 2)
        {
          System.out.print ("\\");
        } 
        else if (b == n / 2)
        {
          System.out.print ("*");
        }
        else if (b > n / 2)
        {
          System.out.print ("/");
        }
      }
       System.out.println ();
     }
    }
  }
}

what im supposed to get

what i get:

Answer 1

These questions are not really for SO but... So what you're doing wrong is that you are trying to put everything into a single loop. While this is possible it makes the code complex and difficult to track. I can fix this but you have just too many miscalculations of when to print / and when to print . So I just simplified it for you:

Do this for half of the times: 1. output the spaces

2. output the /

3. output the *

4. output the \\

Now do everything in reverse for the 2nd half.

public class Main
{
  public static void main (String[]args)
  {
   int n = 7;
    {
      for (int i = 0; i < n/2; i++)
        {
         for (int a = 0; a < (n/2-(i+1)); a++)
         {
          System.out.print (" ");
         }

     for (int b = 0; b < i; b++)
     {

       System.out.print ("/");
     }


       System.out.print ("*");

     for (int c = 0; c < i; c++)
     {

       System.out.print ("\\");
     }
     System.out.println ();

   }

   for (int i = n/2-1; i >= 0; i--)
    {
     for (int a = 0; a < (n/2-(i+1)); a++)
     {
      System.out.print (" ");
     }

     for (int b = 0; b < i; b++)
     {

       System.out.print ("\\");
     }


       System.out.print ("*");

     for (int c = 0; c < i; c++)
     {

       System.out.print ("/");
     }
     System.out.println ();

   }

 }
 }
}

Answer 2

I just rewrote the whole thing, just wanted to share;

public static void main(String[] args) {

    String star = "*";
    String for_slash = "/";
    String back_slash = "\\";
    String space = " ";

    int n = 4;
    for (int i = 0; i < n; i++) {
        String line = "";
        int d = i % n;
        for (int l = n - 1; l > 0; l--) {
            line += ((l < (d + 1)) ? for_slash : space) + space;
        }
        line += star;
        for (int l = 0; l < n - 1; l++) {
            line += space + ((l < d) ? back_slash : space);
        }
        System.out.println(line);
    }
    for (int i = 0; i < n; i++) {
        String line = "";
        int d = i % n;
        for (int l = 0; l < n - 1; l++) {
            line += ((l > (d - 1)) ? back_slash : space) + space;
        }
        line += star;
        for (int l = n - 1; l > 0 ; l--) {
            line += space + ((d < l) ? for_slash : space);
        }
        System.out.println(line);
    }
}

You can edit the spacing etc. yourself

n = 6
          *          
        / * \        
      / / * \ \      
    / / / * \ \ \    
  / / / / * \ \ \ \  
/ / / / / * \ \ \ \ \
\ \ \ \ \ * / / / / /
  \ \ \ \ * / / / /  
    \ \ \ * / / /    
      \ \ * / /      
        \ * /        
          *