删除代码上方和下方的水平线 - 列表包

Question

我怎样才能删除此处代码上方和下方的黑线：

\usepackage{listings}
\usepackage{color}

\definecolor{dkgreen}{rgb}{0,0.6,0}
\definecolor{gray}{rgb}{0.5,0.5,0.5}
\definecolor{mauve}{rgb}{0.58,0,0.82}
\definecolor{codegreen}{rgb}{0,0.6,0}
\definecolor{codegray}{rgb}{0.5,0.5,0.5}
\definecolor{codepurple}{rgb}{0.58,0,0.82}
\definecolor{backcolour}{rgb}{0.95,0.95,0.92}
\definecolor{orange}{RGB}{255,127,0}

\lstset{frame=tb,
  language=Java,
  aboveskip=3mm,
  belowskip=3mm,
  showstringspaces=false,
  columns=flexible,
  basicstyle={\small\ttfamily},
  numbers=left, %eller none
  numberstyle=\tiny\color{codegray},
  keywordstyle=\color{mauve},
  commentstyle=\color{gray},
  stringstyle=\color{orange},
  breaklines=false,
  breakatwhitespace=true,
  tabsize=3,
  backgroundcolor=\color{backcolour},  
}


\begin{document}
{\setlength{\parindent}{0cm}

\begin{lstlisting}
// some comment
import javax.swing.JApplet;
import java.awt.Graphics;

public class Hello extends JApplet {
    public void paintComponent(Graphics g) {
        g.drawString("Hello, world!", 65, 95);
    }    
}
\end{lstlisting}


}
\end{document}

Answer 1

回答我自己的问题：

我找到了代码底部和顶部的行的原因。其为frame=tb。应将其更改为frame=none。