title: Convert List<List<String>> to ArrayList<String> in Android
body: <p>I want to convert them to ArrayList and I will store them. After that, I have to convert them into old values. Do you have any suggestions? Thanks in advance.</p>
  
  <pre><code>public List&lt;List&lt;String&gt;&gt; phones = new ArrayList&lt;&gt;();
  public List&lt;List&lt;Restaurant.Menu&gt;&gt; menus = new ArrayList&lt;&gt;(); 
  
  public ArrayList&lt;String&gt; phones = ?
  public ArrayList&lt;String&gt; menus = ?
  </code></pre>