title: Java unchecked or unsafe operations message
body: <p>I am getting the following error when compiling a <strong>Java</strong> class in <strong>BlueJ</strong>.</p>
  
  <pre><code>AuctionManager.java uses unchecked or unsafe operations.
  </code></pre>
  
  <p>This error is only displayed when the following deserialization code is in one of my functions:</p>
  
  <pre><code>try {
    ObjectInputStream in = new ObjectInputStream(new FileInputStream(Filename));
    ArrayList&lt;AuctionItem&gt; AuctionList = (ArrayList&lt;AuctionItem&gt;) in.readObject();
    in.close();
  }
  catch (Exception e) {
    e.printStackTrace();
  }
  </code></pre>
  
  <p>Can I please have some information as to why this error is being displayed, and some help to use the deserialization code without the error.</p>