title: Should I bother to return empty list if array of zero length exists?
body: <p>Taking this constructor as an example:</p>
  
  <pre><code>private final List&lt;ArrayList&lt;Integer&gt;&gt; adjList;
  public Graph(int vertexCount) {
          adjList = new ArrayList&lt;ArrayList&lt;Integer&gt;&gt;(vertexCount);
          for (int i = 0; i &lt; vertexCount; i++) {
              adjList.add(new ArrayList&lt;Integer&gt;());
          }
      }
  </code></pre>
  
  <p>Here is someone wants a list of vertexes he would simply provide the vertex. </p>
  
  <pre><code>   public List&lt;Integer&gt; adj(int vertex) {
          return adjList.get(vertex); 
      }
  </code></pre>
  
  <p>Now if the vertex did not have any nodes connected to it, then the the return value would be list of size 0.
  Is it of an advantage to return a an Collections.Empty_List by adding an explicit check like: if list size is 0  then return Collections.Empty_List ?</p>