拦截 jTable 选择更改事件

Question

我发现 this forum thread 建议覆盖 ListSelectionModel 以防止行被选中。

当当前所选项目存在未保存的更改（表外部）时，我想防止选择更改，直到用户确认丢弃。比如：

public class confirmSelectionChange extends DefaultListSelectionModel {
    public void setSelectionInterval(int index0, int index1) {
        if (unsavedChanges()) {
            super.setSelectionInterval(int index0, int index1);
        }
    }

    private boolean unsavedChanges() {
        if (noUnsavedChangesExist) {
            return true;
        }

        // Present modal dialog: save, discard cancel
        if (dialogAnswer == SAVE) {
            // save changes
            return true;
        } else if (dialogAnswer == DISCARD) {
            return true;
        } else {
            return false;
        }
    }
}

是否可以在 ListSelectionModel 更改中间插入阻塞代码？有没有更好的方法来拦截选择更改事件？

我已经在听他们的了，但到那时变化已经发生了。

Answer 1

我的最终解决方案（部分感谢this code guru）是创建一个匿名内部类，该类扩展JTable 并覆盖changeSelection()。尝试了一个单独的类，因为我读到有些人认为匿名内部类不是好的 OO 设计，但我需要了解编辑状态，而且我必须调用保存/丢弃方法。当它是你自己的代码时，谁需要封装？ ;-)

jTableMemberList = new JTable() {
    public void changeSelection(int rowIndex, int columnIndex, boolean toggle,
                                boolean extend) {
        // Member is being edited and they've clicked on a DIFFERENT row (this
        // method gets called even when the selection isn't actually changing)
        if (editModeIsActive && getSelectedRow() != rowIndex) {
            // User was editing, now they're trying to move away without saving
            Object[] options = {"Save", "Discard", "Cancel"};
            int n = JOptionPane.showOptionDialog(this,
                                            "There are unsaved changes for the "
                                            + "currently selected member.\n\n"
                                            + "Would you like to save them?",
                                            "Save changes?",
                                            JOptionPane.YES_NO_CANCEL_OPTION,
                                            JOptionPane.WARNING_MESSAGE,
                                            null,
                                            options,
                                            options[0]);

            if (n == JOptionPane.YES_OPTION) {
                saveChanges();
            } else if (n == JOptionPane.NO_OPTION) {
                discardChanges();
            } else {
                // Exit without passing call on to super
                return;
            }
        }

        // make the selection change
        super.changeSelection(rowIndex, columnIndex, toggle, extend);
    }
};

到目前为止，此解决方案似乎有效，但我尚未对其进行广泛测试。这段代码的某个阴暗角落可能潜伏着错误或陷阱……

希望对其他人有所帮助！