title: Java HashMap: adding to arraylist
body: <p>I'm using the HashMap class and it looks like this:</p>
  
  <pre><code>HashMap&lt;String, ArrayList&lt;String&gt;&gt; fileRank = new HashMap&lt;String, ArrayList&lt;String&gt;&gt;();
  </code></pre>
  
  <p>I'm wondering how to add a new String into the Arraylist after the initial put.</p>
  
  <pre><code>fileRank.put(word, file1);
  </code></pre>
  
  <p>I would like to add file2 after file1 to the key: word from above. </p>