How to use example code (of any language) and reference it?

Question

How to use Java or any code in LaTeX and refer it in my document?

Answer 1

Here is an example using the listings package. You use the label option to specify the label, and then refer to it using the usual \ref:

Notes:

• Requires two runs to resolve the reference. In the first run you will see ??, and in the second this will get replaced with the actual listing number.

Code:

\documentclass{article}
\usepackage{filecontents}
\usepackage{listings}

\begin{filecontents*}{foo.java}
 public int nextInt(int n) {
     if (n<=0)
        throw new IllegalArgumentException("n must be positive");

     if ((n & -n) == n)  // i.e., n is a power of 2
         return (int)((n * (long)next(31)) >> 31);

     int bits, val;
     do {
         bits = next(31);
         val = bits % n;
     } while(bits - val + (n-1) < 0);
     return val;
 }
\end{filecontents*}


\lstdefinestyle{MyListStyle} {
    numbers=left,
    numberstyle=\small,
    language=Java
    }
\begin{document}
\lstinputlisting[
    style=MyListStyle,
    linerange={2-6},
    firstnumber=2,
    caption={Partial Listing},
    label={lst: partial}
    ]{foo.java}

As can be seen from Listings~\ref{lst: partial} we see that...
\end{document}