title: Calling method on object in Java 8 stream after collecting
body: <p>Suppose I have this bit of code:</p>
  
  <pre><code>Map&lt;Consumer, Item&gt; map = myStream.parallel()
          .filter(Objects::nonNull)
          .collect(Collectors.toConcurrentMap(e-&gt;e,
                  e-&gt;e, mergeFunction));
  </code></pre>
  
  <p>What I want to do is call a method on each object of the stream after collecting is done.</p>
  
  <p>For example,                 </p>
  
  <pre><code>item.setDate(item.getOneDate());
  </code></pre>
  
  <p>Before the code done sequentially looped through items, put into a map, and at the very end called a bit of the code like the one above, setting a 'date'.</p>
  
  <pre><code>while(iterator.hasNext()) {
     Item blah = iterator.next();
     ....
     // code for putting into map
     ...
     blah.setDate(blah.getOneDate());
  }
  </code></pre>
  
  <p>Not sure how to do this with Java 8 streams. <code>forEach</code>? <code>peek</code>?</p>