title: Java swing scrollpane doesn't show the scroll bar
body: <p>I was working on a java swing gui project for my course. When I was doing that, I found that I had too much information in a panel and it was not able to show everything. As a result, I wanted to add a Jscrollpane and I did some research about how to use this function but it didn't seem to work for my project, and I had no reason why even after I tried almost everything I could find on google.
  Here is my code:</p>
  <pre><code>JFrame frame = new JFrame();
  JPanel listpanel = new JPanel();
  JScrollPane musiclist = new JScrollPane();
  JButton selectButton = new JButton(&quot;Select song&quot;);
  frame.setTitle(&quot;Music Player&quot;);
  frame.getContentPane().setBackground(Color.DARK_GRAY);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setLayout(null);
  frame.setBounds(190,100,840,600);
  Container c = frame.getContentPane();
  musiclist.setViewportView (listpanel);
  musiclist.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
  musiclist.setPreferredSize(new Dimension(10, 1100));
  musiclist.setBounds(0, 0, 190, 1000);
  musiclist.setLayout(null);
  listpanel.setLayout(null);
  listpanel.setBackground(Color.GRAY);
  listpanel.setBounds(0, 10, 160, 600);
  selectButton.setBounds(55,20,100,30);
  selectButton.setOpaque(true);
  selectButton.setBackground(Color.LIGHT_GRAY);
  selectButton.setBorder(null);
  selectButton.setBorderPainted(false);
  listpanel.add(selectButton);
  c.add(musiclist, BorderLayout.WEST);
  frame.setVisible(true);
  musiclist.setVisible(true);
  </code></pre>
  <p>The problem now is that the scroll bar never shows up even I set the vertical to always show. I am just new to java, so any help will be helpful and thank you all for your time!</p>