Working with Loops:
The Triangle class.

Here is a program that solves one of the practice problems for the final exam. 

// Triangle.java: print a triangle
public class Triangle {
   public static void main (String[] args) {
      int n = 10;
      chars(1, '*'); chars(1, '\n');
      for (int line = 2; line < n; line ++) {
         chars(1, '*'); chars(line-2, ' ');
         chars(1, '*'); chars(1, '\n');
      }
      chars(n, '*'); chars(1, '\n');
   }

   public static void chars(int n, char ch) {
      for(int i = 0; i < n; i++)
         System.out.print(ch);
   }  
}
The output. 

*
**
* *
*  *
*   *
*    *
*     *
*      *
*       *
**********