jtable的快速问题

我已经设置了我的框架,左边是jtree,右边是jtable,并使用borderlayout来完成这项工作。然而,一旦我在jtable中放入任何数据,它就会扩展到几乎覆盖整个框架,并用它覆盖我的jtree。表中目前根本没有数据(我正在验证我的SelectionListener),只有几个列标题,总共15个字符。它不可能需要额外的空间。

这是我的设置代码:

    primaryframe = new javax.swing.JFrame();
    primaryframe.setTitle("Bus Route Finder");
    primaryframe.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
    primaryframe.setSize(500, 500);
    primaryframe.setLayout(
        new java.awt.BorderLayout()
    );

    // Set up the tree and it's dependent objects(model, scrollpane, etc).
    javax.swing.tree.DefaultMutableTreeNode node = new javax.swing.tree.DefaultMutableTreeNode(dataroot.GetName());
    node.setUserObject(dataroot);
    CreateNodes(dataroot, node);
    primaryframe.add(
        treescrollpane = new javax.swing.JScrollPane(
            datatree = new javax.swing.JTree(
                treemodel = new javax.swing.tree.DefaultTreeModel(
                    node
                )
            )
        ),
        java.awt.BorderLayout.WEST
    );
    datatree.addTreeSelectionListener(new javax.swing.event.TreeSelectionListener() {
        public void valueChanged(javax.swing.event.TreeSelectionEvent e) {
            javax.swing.JTree tree = (javax.swing.JTree)e.getSource();
            javax.swing.tree.DefaultMutableTreeNode newnode = (javax.swing.tree.DefaultMutableTreeNode)tree.getSelectionPath().getLastPathComponent();
            Controller.TreeData data = (Controller.TreeData)newnode.getUserObject();
            tablemodel.setNumRows(0);
            tablemodel.setColumnCount(0);
            for(int i = 0; i < data.GetNumberOfFields(); i++) {
                tablemodel.addColumn(data.GetFieldName(i));
            }
        }
    });

    primaryframe.add(
        tablescrollpane = new javax.swing.JScrollPane(
            datatable = new JTable(
                tablemodel = new javax.swing.table.DefaultTableModel()
            )
        ),
        java.awt.BorderLayout.EAST
    );