Java Jtree内部JScrollPanel不工作

我从网上得到了新的树示例，但是当我试图显示它时，它没有出现！我不知道为什么。有什么想法吗？ 谢谢大家!

将代码调整为，在这里效果很好

DefaultMutableTreeNode myComputer = new DefaultMutableTreeNode("My Computer");
DefaultMutableTreeNode c = new DefaultMutableTreeNode("Local Disk(C:)");
DefaultMutableTreeNode vinod = new DefaultMutableTreeNode("Vinod");
DefaultMutableTreeNode swing = new DefaultMutableTreeNode("Swing");
DefaultMutableTreeNode tr = new DefaultMutableTreeNode("Tree");
DefaultMutableTreeNode a = new DefaultMutableTreeNode("3½ Floppy(A:)");
DefaultMutableTreeNode e = new DefaultMutableTreeNode("New Volume(E:)");
c.add(vinod);
vinod.add(swing);
swing.add(tr);
myComputer.add(c);
myComputer.add(a);
myComputer.add(e);


JTree tree = new JTree(myComputer);
JScrollPane scrollPane = new JScrollPane(tree);
jPanel1.add(scrollPane);
tree.setVisible(true);

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日志中有错误吗？没有。我要为这件事发疯了@user2712751:另请参见。问题是我没有框架，我正在处理内部框架。@user2712751这不会有任何区别。调整SSCCE以使用内部框架，并查看是否可以重现问题。如果没有，请在示例中将滚动窗格添加到ContentPane中，查找与实际应用程序的差异。我想把它添加到JPanel中。

  public static void main( String[] args ) {
    EventQueue.invokeLater( new Runnable() {
      @Override
      public void run() {
        JFrame frame = new JFrame();

        DefaultMutableTreeNode myComputer = new DefaultMutableTreeNode("My Computer");
        DefaultMutableTreeNode c = new DefaultMutableTreeNode("Local Disk(C:)");
        DefaultMutableTreeNode vinod = new DefaultMutableTreeNode("Vinod");
        DefaultMutableTreeNode swing = new DefaultMutableTreeNode("Swing");
        DefaultMutableTreeNode tr = new DefaultMutableTreeNode("Tree");
        DefaultMutableTreeNode a = new DefaultMutableTreeNode("3½ Floppy(A:)");
        DefaultMutableTreeNode e = new DefaultMutableTreeNode("New Volume(E:)");
        c.add(vinod);
        vinod.add(swing);
        swing.add(tr);
        myComputer.add(c);
        myComputer.add(a);
        myComputer.add(e);


        JTree tree = new JTree(myComputer);
        JScrollPane scrollPane = new JScrollPane(tree);
        frame.getContentPane().add(scrollPane);
        tree.setVisible(true);

        frame.setDefaultCloseOperation( WindowConstants.EXIT_ON_CLOSE );
        frame.pack();
        frame.setVisible( true );
      }
    } );
  }