java - JTable.columnMoved 方法的一个错误

Question

javax.swing.JTable 有一个错误，如果我们在编辑空值单元格时对表格进行排序，并且其列类没有带有“new Object[] { new String() }”参数的构造函数，例如。长类，JTable 将抛出异常。

我认为这是因为 javax.swing.JTable 两次尝试删除单元格编辑器；所以我计划将 JTable.columnMoved 方法重写为:

@Override
public void columnMoved(TableColumnModelEvent e) {
    if (isEditing() && !getCellEditor().stopCellEditing()) {
        if(getCellEditor() != null) { // In javax.swing.JTable, no this check point
            getCellEditor().cancelCellEditing();
        }
    }
    repaint();
}

我觉得这还不够好，因为它对代码阅读者不友好，他们可能对 JTable 很了解，并且不喜欢我这样的子类。有更好的解决方案吗？非常感谢。

运行以下代码时，双击一个单元格(不要输入任何内容)，然后单击标题，将出现异常。

public class NewJFrame extends javax.swing.JFrame {

    public NewJFrame() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jScrollPane1 = new javax.swing.JScrollPane();
        jTable1 = new javax.swing.JTable();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jTable1.setModel(new javax.swing.table.DefaultTableModel(
            new Object [][] {
                {null, null},
                {null, null},
                {null, null},
                {null, null}
            },
            new String [] {
                "Title 1", "Title 2"
            }
        ) {
            Class[] types = new Class [] {
                java.lang.Long.class, java.lang.Long.class
            };

            public Class getColumnClass(int columnIndex) {
                return types [columnIndex];
            }
        });
        jScrollPane1.setViewportView(jTable1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 375, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(15, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 275, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(14, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new NewJFrame().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTable jTable1;
    // End of variables declaration
}

Answer 1

我可以使用您提供的代码重现该问题。我责怪 JTable#stopCellEditing 实现

    public boolean stopCellEditing() {
        String s = (String)super.getCellEditorValue();
        // Here we are dealing with the case where a user
        // has deleted the string value in a cell, possibly
        // after a failed validation. Return null, so that
        // they have the option to replace the value with
        // null or use escape to restore the original.
        // For Strings, return "" for backward compatibility.
        if ("".equals(s)) {
            if (constructor.getDeclaringClass() == String.class) {
                value = s;
            }
            super.stopCellEditing();
        }

        try {
            value = constructor.newInstance(new Object[]{s});
        }
        catch (Exception e) {
            ((JComponent)getComponent()).setBorder(new LineBorder(Color.red));
            return false;
        }
        return super.stopCellEditing();
    }

您输入第一个 if，其中 super.stopCellEditing 被调用。此调用的返回值将被忽略。然后 newInstance 调用抛出一个异常，该异常被捕获但随后返回 false，无论 super.stopCellEditing 的返回值是什么。这对我来说听起来不正确。我会用你提供的代码记录 Oracle 的错误