title: Why the use of open bracket and close bracket to declare a variable in Java
body: <p>Can someone please explain the use of the following code in Java</p>
  <pre><code>private TableColumn&lt;Books, Integer&gt; colId;
  </code></pre>
  <p>I want to know the reason of using <code>&lt;?,?&gt;</code> to declare a variable in Java.</p>