title: List<String> to ArrayList<String> conversion issue
body: <p>I have a following method...which actually takes the list of sentences and splits each sentence into words. Here is it:</p>
  <pre><code>public List&lt;String&gt; getWords(List&lt;String&gt; strSentences){
  allWords = new ArrayList&lt;String&gt;();
      Iterator&lt;String&gt; itrTemp = strSentences.iterator();
      while(itrTemp.hasNext()){
          String strTemp = itrTemp.next();
          allWords = Arrays.asList(strTemp.toLowerCase().split(&quot;\\s+&quot;));          
      }
      return allWords;
  }
  </code></pre>
  <p>I have to pass this list into a hashmap in the following format</p>
  <pre><code>HashMap&lt;String, ArrayList&lt;String&gt;&gt;
  </code></pre>
  <p>so this method returns List and I need an ArrayList? If I try to cast it doesn't work out... any suggestions?</p>
  <p>Also, if I change the ArrayList to List in a HashMap, I get</p>
  <pre><code>java.lang.UnsupportedOperationException
  </code></pre>
  <p>because of this line in my code</p>
  <pre><code>sentenceList.add(((Element)sentenceNodeList.item(sentenceIndex)).getTextContent());
  </code></pre>
  <p>Any better suggestions?</p>