如何让TableSorter保持固定位置？

Question

我有一张桌子，而我使用DefaultTableModel。我实现了一个TableListener以确保第一列中没有空值并删除重复项。此外，我添加一个空行作为表中的最后一行，因此当用户输入一个不存在的值时，它将被添加到行中。

现在我想保留列的排序并将TableRowSorter添加到我的模型中。但现在问题是空行也被排序。我实现了Comparator，因为我认为我可以通过检查空列来覆盖这一点，但这不起作用，因为我不知道分拣机目前订购的方向。

有没有办法做到这一点（有空行作为最后一行总是）？我能否以某种方式获得排序顺序？或者我必须为此仅实现一个完整的模型？

Answer 1

我找到了解决方案。这里是完整的课程供参考。

public class EnvironmentPanel 
    extends JPanel 
    implements Comparator<String> 
{ 
    private static final long serialVersionUID = 1L; 

    private static final String[] mHeader = 
    { 
     "Name", 
     "Value", 
    }; 

    private JTable mEnvironmentTable = null; 
    private DefaultTableModel mTableModel = null; 
    private int mSortOrder = 1; 

    public EnvironmentPanel() 
    { 
     initialize(); 
    } 

    private void initialize() 
    { 
     GridBagLayout gridBagLayout = new GridBagLayout(); 
     setLayout(gridBagLayout); 

     JScrollPane scrollPane = new JScrollPane(); 
     scrollPane.setViewportBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null)); 

     GridBagConstraints gbc_scrollPane = new GridBagConstraints(); 
     gbc_scrollPane.insets = new Insets(3, 3, 3, 3); 
     gbc_scrollPane.weighty = 1.0; 
     gbc_scrollPane.weightx = 1.0; 
     gbc_scrollPane.fill = GridBagConstraints.BOTH; 
     gbc_scrollPane.anchor = GridBagConstraints.NORTHWEST; 
     gbc_scrollPane.gridx = 0; 
     gbc_scrollPane.gridy = 0; 
     add(scrollPane, gbc_scrollPane); 

     scrollPane.setViewportView(getMEnvironmentTable()); 
    } 

    private JTable getMEnvironmentTable() 
    { 
     if(mEnvironmentTable == null) 
     { 
      mEnvironmentTable = new JTable(); 
      mEnvironmentTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); 
      mTableModel = new DefaultTableModel(); 
      mEnvironmentTable.setModel(mTableModel); 
      for(int i = 0; i < mHeader.length; i++) 
       mTableModel.addColumn(mHeader[i]); 
      Object[] row = new Object[mHeader.length]; 
      row[0] = ""; 
      mTableModel.addRow(row); 
      TableRowSorter<TableModel> sorter = new TableRowSorter<TableModel>(); 
      mEnvironmentTable.setRowSorter(sorter); 
      sorter.setModel(mTableModel); 
      sorter.setComparator(0, this); 
      sorter.setSortsOnUpdates(true); 
      sorter.addRowSorterListener(new RowSorterListener() 
      { 
       @Override 
       public void sorterChanged(RowSorterEvent oEvent) 
       { 
        if(oEvent.getType().equals(Type.SORT_ORDER_CHANGED)) 
         mSortOrder *= (-1); 
       } 
      }); 

      mTableModel.addTableModelListener(new TableModelListener() 
      { 
       public void tableChanged(TableModelEvent oEvent) 
       { 
        onTableChanged(oEvent); 
       } 
      }); 
     } 
     return mEnvironmentTable; 
    } 

    /** 
    * The table will always have an empty line at the end. If a new name is entered 
    * the value is taken and a new line will be added. 
    * Entries with an empty name column will be removed. 
    * 
    * The name must be unique. 
    * 
    * @param oEvent 
    */ 
    private void onTableChanged(TableModelEvent oEvent) 
    { 
     String s = null; 
     Map<String, Integer>nmap = new HashMap<String, Integer>(); 

     for(int i = mTableModel.getRowCount()-2; i >= 0; i--) 
     { 
      s = (String)mTableModel.getValueAt(i, 0); 
      if(s == null || s.equals("")) 
      { 
       mTableModel.removeRow(i); 
       continue; 
      } 

      // If we found an entry with the same name, we remove the one 
      // that is later in the list. 
      if(nmap.containsKey(s)) 
      { 
       int pos = nmap.get(s); 
       mTableModel.removeRow(pos); 
      } 

      // Add the latest row to the map. 
      nmap.put(s, i); 
     } 

     int n = mTableModel.getRowCount(); 
     if(n > 0) 
     { 
      s = (String)mTableModel.getValueAt(n-1, 0); 
      if(s != null && s.equals("") == false) 
      { 
       Object[] row = new Object[mHeader.length]; 
       row[0] = ""; 
       mTableModel.addRow(row); 
      } 
      else 
      { 
       s = (String)mTableModel.getValueAt(n-1, 1); 
       if(s != null && s.equals("") == false) 
        mTableModel.setValueAt(null, n-1, 1); 
      } 
     } 
    } 

    @Override 
    public int compare(String oLeft, String oRight) 
    { 
     if(oLeft.equals("")) 
      return -1*mSortOrder; 

     if(oRight.equals("")) 
      return 1*mSortOrder; 

     return oLeft.compareTo(oRight); 
    } 
}