title: What is the meaning of the leading underline of "val = _val"? Does it have some deep use or deep meaning? In Java
body: <p>In one algorithm question &quot;Implement Queue by Linked List&quot;, the solution shows create the class Node first:</p>
  <pre><code>class Node {
      public int val;
      public Node next;
      public Node(int _val) {
          val = _val;
          next = null;
      }
  }
  </code></pre>
  <p>May I ask the meaning of the leading underline of <code>val = _val</code>?</p>