toString())</tt>
 (which typically contains the class and detail message of
 <tt>cause</tt>).  This constructor is useful for runtime exceptions
 that are little more than wrappers for other throwables.</div>
<dl>
<dt><span class="paramLabel">参数:</span></dt>
<dd><code>cause</code> - the cause (which is saved for later retrieval by the
              <code>Throwable.getCause()</code> method).  (A <tt>null</tt> value is
              permitted, and indicates that the cause is nonexistent or
              u