title: Find sum of diagonal elements in array using Java 8 streams
body: <p>Need to find sum of respective diagonal elements using java 8 streams.     </p>
  
  <pre><code>2d Array - { 
               { 1, 2, 3 },
               { 5, 6, 7 },
               { 8, 2, 3 }
             }
  
  Output - Sum1 (1+6+3) = 10
           Sum2 (3+6+8) = 17
  </code></pre>
  
  <p>I know to do this by for looping array. Can this done using Java 8 stream ? If yes, how ?</p>