添加JPanel时的JTable列头dissapear

Question

somePanel=new JPanel (new FlowLayout ());
somePanel.setPreferredSize (new Dimension (600,50));
somePanel.setBackground (Color.lightGray);

mainPane=new JPanel (new BorderLayout ());
mainPane.setPreferredSize (new Dimension (600,550));
mainPane.setBackground (Color.lightGray);
mainPane.add (somePanel,BorderLayout.NORTH);
mainPane.add (table,BorderLayout.CENTER);

scrollBar=new JscrollBar();
scrollBar.setVisible (true);
scrollBar.setVisibleAmount (10);
scrollBar.setEnabled (true);
scrollBar.setOrientation (Adjustable.VERTICAL);

scrollPane=new JScrollPane ();
scrollPane.setVerticalScrollBar (scrollBar);
scrollPane.setVerticalScrollBarPolicy 
(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
scrollPane.setPreferredSize (new Dimension (600,650));
scrollPane.setViewportView (mainPane);



/*the createExamsSchedualTable()  is inside inner class in the Jframe 
and called by class constructor*/
private void createExamsSchedualTable(){
table=new JTable (new TheTableModel ());
table.setPreferredScrollableViewportSize (new Dimension (600,570));
table.setFillsViewportHeight (true);
table.setAutoResizeMode (JTable.AUTO_RESIZE_ALL_COLUMNS);
table.setAutoCreateRowSorter (true);
table.setSelectionBackground (Color.LIGHT_GRAY);
table.setDragEnabled (true);
table.setGridColor (Color.LIGHT_GRAY);
table.setIntercellSpacing (new Dimension (3,3));
table.setRowSelectionAllowed (true);
table.setColumnSelectionAllowed (true);
table.setCellSelectionEnabled (true);
table.setShowGrid (true);
table.setShowHorizontalLines (true);
table.setVerifyInputWhenFocusTarget (true);
table.setToolTipText ("Exams Scheduals Times Table");
}
/*TheTableModel class extends AbstractTableModel */

Answer 1

还是不知道为什么头消失了！！

当您将JTable添加到JScrollPane时，JTable的JTableHeader将添加到滚动窗格的列标题中。这是JTable的特殊逻辑。

如果您直接将JTable添加到JPanel中，那么您将负责在面板上显示header。类似于：

JPanel panel = new JPanel( new BorderLayout() );
panel.add(table, BorderLayout.CENTER);
panel.add(table.getTableHeader(), BorderLayout.PAGE_START);
panel.add(anotherPanel, BorderLayout.PAGE_END);

JPanel panel = new JPanel(...);
panel.add(table, ...);
panel.add(anotherPanel, ...);
JScrollPane scrollPane = new JScrollPane(panel);
scrollPane.setColumnHeaderView(table.getTableHeader());