title: calculate and return the sum of all the even numbers in the 2d-array in java
body: <p>This Matrix class takes a <code>int[][]</code> as a parameter and saves it in
  the instance variable.</p>
  
  <p>I need to complete the <code>sumOfEvenNumbers</code> method to calculate and return the sum of all the even numbers in the array.</p>
  
  <pre><code>public class Matrix
  {
      private int[][] matrix;
  
      /**
       * Gets the sum of all the even numbers in the matrix
       * @return the sum of all the even numbers
       */
      public int sumOfEvenNumbers()
      {
          int sum = 0;
          for (int[] i: array)                          
          if (i%2 == 0){ 
          sum += i;        
          }
          return sum;
           // TODO: Return the sum of all the numbers which are even
      }
  }
  </code></pre>