title: How to check if an element in array exists in Java
body: <p>If I have an <code>int</code> array structured like this:</p>
  
  <pre><code>private int[][] map = new int[400][400];
  </code></pre>
  
  <p>And I try to retrieve</p>
  
  <pre><code>map[100][200]
  </code></pre>
  
  <p>And that element isn't initialized, will i get a compiler/runtime error or will it return null? And is there any function to check if a given element/index exists/has been set?</p>