\usepackage{listings}

\begin{listing}[H]
\begin{minted}
[
baselinestretch=1.1,
bgcolor=clcodeshade,
fontsize=\footnotesize,
linenos
]
{Java}
public abstract class Event
{
    private Answer leadingAnswer;

    public Event ()
    {
        leadingAnswer = null;
    }

    public void addLeadingAnswer (Answer answer) throws LeadingAnswerAllreadySetException
    {
        if (leadingAnswer != null)
        {
            throw new LeadingAnswerAllreadySetException();
        }

        if (answer != null)
        {
            leadingAnswer = answer;
        } else
        {
            throw new NullPointerException();
        }
    }

    public void changeLeadingAnswer (Answer newAnswer)
    {
        if (newAnswer == null)
        {
            throw new NullPointerException();
        } else
        {
            leadingAnswer = newAnswer;
        }
    }

    public Answer getLeadingAnswer ()
    {
        return leadingAnswer;
    }
}
\end{minted}
\caption{Klassen event}
\label{ParentClassEvent}
\end{listing}