title: Java stream reduce to map
body: <p>I got array list of strings, how could I reduce them to hash map</p>
  
  <p>Input: <code>[a, b, a, a, c, x]</code></p>
  
  <p>Output: <code>{(a: 3), (b: 1), (c: 1), (x: 1)}</code></p>
  
  <p>PS. I searched for this. I need to do that with <code>reduce</code> not with frequency counting as in other questions, because my question is a simplified real task.</p>