使用多个复选框创建一个组合框

Question

我已阅读文档和教程，并在此处搜索，但无济于事。

Oracle tutorial: how to use custom render for ComboBox

Another question similar with a somehow vague answer

而且我认为这很重要，因为很多人都在询问它，但没有人可以提供一个简单，可行的例子。所以我必须自己问一下：

我们如何使用下拉菜单制作组合框，允许我们选择多个选项？

什么不起作用：

• JList在这里被证明是没用的，因为我不能让它出现在下拉菜单中。
• Swing中没有CheckBoxList。

我在组合的下拉菜单中选中了复选框SCCEE，但复选框拒绝被选中，框中的复选框丢失了。

我们怎样才能做到这一点？

import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.util.List;

import javax.swing.DefaultCellEditor;
import javax.swing.DefaultListModel;
import javax.swing.DefaultListSelectionModel;
import javax.swing.JCheckBox;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JTable;
import javax.swing.ListCellRenderer;
import javax.swing.ListSelectionModel;
import javax.swing.SwingUtilities;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.table.TableColumn;

public class ComboOfCheckBox extends JFrame {

public ComboOfCheckBox() {
    begin();
}

private void begin() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel();

    JTable table = new JTable(new Object[2][2], new String[]{"COL1", "COL2"});
    final JCheckBox chx1 = new JCheckBox("Oh");
    final JCheckBox chx2 = new JCheckBox("My");
    final JCheckBox chx3 = new JCheckBox("God");
    String[] values = new String[] {"Oh", "My", "God"};
    JCheckBox[] array = new JCheckBox[] {chx1, chx2, chx3};
    final JComboBox<JCheckBox> comboBox = new JComboBox<JCheckBox>(array) {
        @Override
        public void setPopupVisible(boolean visible){
            if (visible) {
                super.setPopupVisible(visible);
            }
        }
    };

    class CheckBoxRenderer  implements ListCellRenderer {

        private boolean[] selected;
        private String[] items;

        public CheckBoxRenderer(String[] items) {
            this.items = items;
            this.selected = new boolean[items.length];
        }

        @Override
        public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected,
                boolean cellHasFocus) {
            JLabel label = null;
            JCheckBox box = null;
            if (value instanceof JCheckBox) {
                label = new JLabel(((JCheckBox)value).getText());
                box = new JCheckBox(label.getText());
            }
            return box;
        }
        public void setSelected(int i, boolean selected) {
            this.selected[i] = selected;
        }

    }

    comboBox.setRenderer(new CheckBoxRenderer(values));

    panel.add(comboBox);    
    panel.add(new JCheckBox("Another"));
    getContentPane().add(panel);
    pack();
    setVisible(true);
}

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

        @Override
        public void run() {
            ComboOfCheckBox frame = new ComboOfCheckBox();

        }   
    });
}
}