JScrollPane没有显示继承的JPanel

Question

我有一个扩展JPanel的类。代码如下：

public class Test extends JPanel implements Testnterface {
    private JScrollPane listScroller;

    DefaultListModel model;
    private JList requestList;    
    public Test() {

        String title = "Stackoverflow Question";
        setBorder(BorderFactory.createTitledBorder(title));
        model = new DefaultListModel();
     requestList = new JList(); // create a list
        listScroller = new JScrollPane(requestList); // create a scrollbar to the list
        listScroller.setPreferredSize(new Dimension(250, 80));

        setLayout(null);
        add(listScroller); // even though I add the scrollPane, nothing is displayed   
    }
 }

我更新了代码。即使我添加它，我似乎也无法将我的JScrollPane显示在我的JPanel上。有人有任何想法吗？

Answer 1

我遇到了同样的问题，并通过使用JPanel包装滚动窗格解决了这个问题：

final JScrollPane jScrollPane = new JScrollPane(list,
     JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
     JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

final JPanel panel = new JPanel(new BorderLayout(BORDER_SIZE, BORDER_SIZE));
panel.setBorder(BorderFactory.createEmptyBorder(BORDER_SIZE, BORDER_SIZE, 
      BORDER_SIZE, BORDER_SIZE));

panel.add(jScrollPane);