\begin{lrbox}{\mycodebox}
\lstset{escapeinside={!}{!}}
\begin{lstlisting}
public class !\iPart{l}{Math}!
....
!\cPart{s}{\bgcode{static} \iPart{r}{double} \iPart{n}{sqrt}(\iPart{a}{double} a)}!
....
\end{lstlisting}
\end{lrbox}

\begin{tikzpicture}[remember picture]
\node(code) [anatomy] at (0,0) {\usebox\mycodebox};

% Annotation
\codeAnnotation{lText}    (3,2.5)   {library name}
\codeAnnotation{sText}   (-1,1)     {signature}
\codeAnnotation{nText}  (4.5,1.5)   {method name}
\codeAnnotation{rText}  (2.0,-0.51) {return type}
\codeAnnotation{aText}  (4.5,-0.51) {argument type}
% Arrows
\draw[->, annotation] (lText) -- (l);
\draw[->, annotation] (nText) -- (n);
\draw[->, annotation] (sText) -- (s);
\draw[->, annotation] (rText) -- (r);
\draw[->, annotation] (aText) -- (a);
\end{tikzpicture}