Look i am not sure about the exact coding, but the way of doing these diamond problem is as follows:
Use two loops. One inside another. Outer loop will be for rows and inner loop for columns. Insert space for middle rows.
for (int i;i<rows.length;i++)
{
for (int j;j<columns.length;j++)
{
//your logic here to check where to insert space to make it diamond
}
}