java - 使用 setAutoCreateRowSorter(true) 时获取列排序顺序？

Question

我有一个 JTable，其中设置了 table.setAutoCreateRowSorter(true);。我的主要目标是无论任何列排序顺序如何，都有一行始终位于顶部。我做的第一件事是修改单元格数据类型的 compareTo 方法，以便它能够理解表示“小于其他任何内容”的标志，因此始终将该项目排序到顶部。不幸的是，这使得给定的行始终位于最顶部或最底部，具体取决于列的排序顺序。因此，当排序顺序为降序时，我需要设置单元格，使其有效值大于。唯一的问题是我不知道如何获取列排序顺序。

关于this page ，一个建议的答案类似于

if (myTable.getRowSorter().getSortKeys().get(column).getSortOrder == SortOrder.ASCENDING) {
    ...
}

不幸的是，getSortKeys()总是返回一个空列表。所以我又回到了原点。我还考虑过添加 RowSorterListener，但这似乎是排序器更改时的监听器，而不是排序顺序更改时的监听器。

有什么帮助吗？谢谢!

编辑:这是演示我的问题的部分代码。请注意 System.out.println，其中结果始终为零。我想获取列的行排序顺序，但似乎不存在。

package tablecolumn;

import java.awt.Dimension;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import javax.swing.GroupLayout;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.RowSorter;
import javax.swing.SortOrder;
import javax.swing.table.AbstractTableModel;

public class Tablecolumn extends JFrame {
    JScrollPane scroll;
    JTable table;
    MyTableModel model;

    static String[] columnnames = new String[] {"A", "B", "C"};

    public class MyTableModel extends AbstractTableModel {
        public List<List<String>> entries;

        MyTableModel() {
            entries = new ArrayList<List<String>>();
            for (int i=0; i<5; i++) {
                List<String> cols = new ArrayList<String>();
                cols.add("X" + i);
                cols.add("Y" + i);
                cols.add("Z" + i);
                entries.add(cols);
            }
        }

        @Override
        public int getRowCount() {
            return entries.size();
        }

        @Override
        public int getColumnCount() {
            return columnnames.length;
        }

        @Override
        public Object getValueAt(int r, int c) {
            List<? extends RowSorter.SortKey> rsk = table.getRowSorter().getSortKeys();
            System.out.println(rsk.size());
            return entries.get(r).get(c);
        }

        @Override
        public Class getColumnClass(int c) { 
            return String.class; 
        }

        @Override
        public String getColumnName(int c) { return columnnames[c]; }        

        @Override
        public boolean isCellEditable(int row, int col) { return false; }

    }

    public Tablecolumn() {
        scroll = new JScrollPane();
        model = new MyTableModel();
        table = new JTable();

        table.setModel(model);
        table.setAutoCreateRowSorter(true);
        table.setAutoResizeMode(javax.swing.JTable.AUTO_RESIZE_ALL_COLUMNS);
        table.getTableHeader().setReorderingAllowed(false);
        table.setColumnSelectionAllowed(false);
        table.setRowSelectionAllowed(true);

        scroll.setViewportView(table);

        scroll.setMinimumSize(new Dimension(200, 200));
        scroll.setPreferredSize(new Dimension(800, 600));

        GroupLayout layout2 = new GroupLayout(this.getContentPane());
        this.setLayout(layout2);
        layout2.setVerticalGroup(
            layout2.createSequentialGroup()
                .addComponent(scroll)
        );
        layout2.setHorizontalGroup(
            layout2.createParallelGroup()
                .addComponent(scroll)
        );               

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        pack();
    }

    public static void main(String[] args) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Tablecolumn().setVisible(true);
            }
        });
    }
}

Answer 1

1)你的问题很简单无法回答，因为你忽略了反复要求发布SSCCE

2)例如

import java.awt.*;
import java.awt.event.*;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
import javax.swing.table.*;
import javax.swing.RowSorter.SortKey;

class SelectedColumnTest {

    private JTableHeader header;
    private Object selectedColumn = null;
    private String[] columnNames = {"String", "Integer", "Boolean"};
    private Object[][] data = {{"aaa", 12, true}, {"bbb", 5, false}, {"CCC", 92, true}};
    private TableModel model = new DefaultTableModel(data, columnNames) {

        private static final long serialVersionUID = 1L;

        @Override
        public Class<?> getColumnClass(int column) {
            return getValueAt(0, column).getClass();
        }
    };
    private JTable table = new JTable(model);

    public JComponent makeUI() {
        table.setRowSorter(new TableRowSorter<TableModel>(model) {

            @Override
            public void toggleSortOrder(int column) {
            }
        });
        header = table.getTableHeader();
        header.getActionMap().put("toggleSortOrder2", new AbstractAction() {

            private static final long serialVersionUID = 1L;

            @Override
            public void actionPerformed(ActionEvent e) {
                e.setSource(table);
                table.getActionMap().get("focusHeader").actionPerformed(e);
                if (selectedColumn != null) {
                    int i = header.getColumnModel().getColumnIndex(selectedColumn);
                    SortOrder order = SortOrder.ASCENDING;
                    List<SortKey> keys = new ArrayList<SortKey>(table.getRowSorter().getSortKeys());
                    if (!keys.isEmpty()) {
                        SortKey sortKey = keys.get(0);
                        if (sortKey.getColumn() == i && sortKey.getSortOrder() == SortOrder.ASCENDING) {
                            order = SortOrder.DESCENDING;
                        }
                    }
                    table.getRowSorter().setSortKeys(Arrays.asList(new SortKey(i, order)));
                }
                header.repaint();
            }
        });
        InputMap im = header.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
        im.put(KeyStroke.getKeyStroke(KeyEvent.VK_F8, 0), "toggleSortOrder2");
        header.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseClicked(MouseEvent e) {
                JTableHeader h = (JTableHeader) e.getSource();
                int i = h.columnAtPoint(e.getPoint());
                Object o = h.getColumnModel().getColumn(i).getHeaderValue();
                if (i < 0 || o == selectedColumn) {
                    selectedColumn = null;
                    return;
                }
                selectedColumn = o;
                h.requestFocusInWindow();
            }
        });
        final TableCellRenderer hr = table.getTableHeader().getDefaultRenderer();
        header.setDefaultRenderer(new TableCellRenderer() {

            @Override
            public Component getTableCellRendererComponent(JTable t, Object v,
                    boolean isS, boolean hasF, int row, int col) {
                return (v == selectedColumn) ? hr.getTableCellRendererComponent(
                        t, v, true, true, row, col) : hr.getTableCellRendererComponent(
                        t, v, false, false, row, col);
            }
        });
        header.setToolTipText("Sorting by F8");
        JPanel p = new JPanel(new BorderLayout());
        p.add(new JScrollPane(table));
        return p;
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                createAndShowGUI();
            }
        });
    }

    public static void createAndShowGUI() {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        f.getContentPane().add(new SelectedColumnTest().makeUI());
        f.setSize(320, 240);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
}

3)当您使用 SSCCE 编辑问题时，准确地演示了您的问题，然后我会查看它

4) 没有比 Darryl's Multisort Table Header Cell Renderer 更好的了。