在细胞选择jtable事件之前

Question

当要选择单元格时是否会触发任何事件？有ListSelectionListener,但它只有在选择发生后触发的事件.我需要一些方法来取消选择事件并使用ListSelectionListener它并不容易,因为选择已经发生,我需要一些状态变量,指示选择是正常还是取消先前的选择.

有没有办法关闭选择通知？然而,这不是100%好的解决方案(如果某些侦听器在其本地存储中保存选择状态会有问题)这总比没有好.

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.ListSelectionModel;
import javax.swing.border.EmptyBorder;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.table.AbstractTableModel;
import javax.swing.JTable;

public class JTableExample extends JFrame {

    /**
     * 
     */
    private static final long serialVersionUID = 6040280633406589974L;
    private JPanel contentPane;
    private JTable table;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    JTableExample frame = new JTableExample();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public JTableExample() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        table = new JTable(new MyTableModel());
        ListSelectionModel selectionModel = table.getSelectionModel();
        selectionModel.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        selectionModel.addListSelectionListener(new MySelectionListener());
        contentPane.add(table, BorderLayout.CENTER);
    }

    class MyTableModel extends AbstractTableModel {
        /**
         * 
         */
        private static final long serialVersionUID = -8312320171325776638L;

        public int getRowCount() {
            return 10;
        }

        public int getColumnCount() {
            return 10;
        }

        public Object getValueAt(int rowIndex, int columnIndex) {
            return rowIndex * columnIndex;
        }
    }

    class MySelectionListener implements ListSelectionListener {
        public void valueChanged(ListSelectionEvent e) {
            int selectedRow = table.getSelectedRow();
            if (selectedRow == 5) {
                System.out.println("I would like this selection never happened.");
            }
        }
    }

}

Answer 1

无论你想达到什么目标:认为"mouseEvent"还不够,选择可能会因其他原因而改变(键盘输入,程序触发器......).恢复侦听器中未经过更改的更改不是一种选择:正如您已经指出的那样,需要保留选区的副本并且可能会混淆其他侦听器.

唯一的方法(我认为,可能是其他人,当然;-) 不是让它首先发生:实现List SelectionModel,如果满足某些条件,它不会改变选择.我最喜欢的(有偏见的:-)是VetoableListSelectionModel它是DefaultListSelectionModel的子类,在SingleSelectionMode中,在实际更改之前等待来自感兴趣方的否决.

这是一个使用它的(原始)代码片段:

    VetoableListSelectionModel vetoableSelection = new VetoableListSelectionModel();
    VetoableChangeListener navigationController = new VetoableChangeListener() {

        public void vetoableChange(PropertyChangeEvent evt)
                throws PropertyVetoException {
            // custom method that implements your condition 
            if (!canSelect((int) evt.getOldValue(), (int) evt.getNewValue()))
                throw new PropertyVetoException("uncommitted changes",
                        evt);
        }

    };
    vetoableSelection.addVetoableChangeListener(navigationController);
    myTable.setSelectionModel(vetoableSelection);