Data Structures, Algorithms, & Applications in Java
Chapter 12, Exercise 23

Since the elements are stored in the array by levels, a level order traversal may be done by examining the array from left to right. The code is given below. The test program and output are in the files ArayBinaryTreeWithLevelOrder.*. 
public class ArrayBinaryTreeWithLevelOrder
{
   static Object [] a;   // array that contains the tree

   /** visit method that prints the element in a[i] */ 
   public static void visit(int i)
      {System.out.print(a[i] + " ");}

   /** level order traversal */
   public static void levelOrder(Object [] theArray, int last)
   {
      a = theArray;
      for (int i = 1; i <= last; i++)
         if (a[i] != null)
            visit(i);  
   }
}