一起实现动作和Item侦听器

Question

以下是我设置的系统，用于跟踪添加到arraylist的面板数量，并在不再需要时删除这些面板。基本上我需要帮助的部分是同时使用JButton的Item / Actionlistener和JCheckBox。我设法存储动态创建的包含arraylist中的textfield和checkboxes的rowpanel，但是将它应用于itemlistener或actionlistener有点令人困惑。我希望删除按钮只删除选中的复选框，但由于checkitem变量超出其范围，我得到一个空指针异常。我觉得如果我能找到解决方法，我相信传递一个局部变量作为参数，我觉得我的删除按钮会起作用。另外我知道rowPanel是一个全局变量是另一个因素，抛出我的所有引用，但删除它，并使其本地我最终与我的删除按钮相同的问题。我的Itemlistener有效，因为我想确保它可以跟踪检查哪些复选框并打印出数组的大小。然而我的另一个问题是我必须选择使用哪个特定的听众，因为我已经阅读过我可以将这两种方法结合在一起吗？

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;

public class UI extends JFrame implements ItemListener {

    JPanel mainPanel, infoPanel, txtFldNames, txtFlds, bttn, checkBox, rowPanel;
    JTextField name, checkOutDate, checkInDate, email;
    JButton add, delete;
    JLabel label1, label2, label3, label4, label5;
    JScrollPane scrollBar;
    ArrayList<Component> checkBoxArrLst = new ArrayList<Component>();

    public UI() {

        txtFldNames = new JPanel(new GridLayout(1, 4, 5, 5));
        label1 = new JLabel("Name", SwingConstants.CENTER);
        label2 = new JLabel("Check Out Date", SwingConstants.CENTER);
        label3 = new JLabel("Check In Date", SwingConstants.CENTER);
        label4 = new JLabel("Email", SwingConstants.CENTER);
        label5 = new JLabel("", SwingConstants.CENTER); // empty label used as a
                                                        // place holder for the
                                                        // checkbox
        txtFldNames.add(label1);
        txtFldNames.add(label2);
        txtFldNames.add(label3);
        txtFldNames.add(label4);
        txtFldNames.add(label5);

        add = new JButton("Add");
        add.addActionListener(e -> {
            JPanel rowPanel = new JPanel(new GridLayout(1, 4, 5, 5));
            JCheckBox checkItem = new JCheckBox();
            checkItem.addItemListener(this);
            for (int i = 0; i < 4; i++) {
                rowPanel.add(new JTextField());
            }
            for (int l = 0; l < 1; l++) {
                rowPanel.add(checkItem, BorderLayout.EAST);
            }
            checkBoxArrLst.add(rowPanel);
            infoPanel.add(rowPanel);
            infoPanel.revalidate();
            infoPanel.repaint();
        });

        delete = new JButton("Delete");
        delete.addActionListener(e -> {
            Component[] components = rowPanel.getComponents();
            for (Component c : components) {
                if (c instanceof JCheckBox) {
                    JCheckBox checkItem = (JCheckBox) c;
                    if (((JCheckBox) c).isSelected()) {
                        infoPanel.remove(checkItem);
                    }
                }
            }

            infoPanel.revalidate();
            infoPanel.repaint();

        });

        bttn = new JPanel(new FlowLayout(FlowLayout.CENTER));
        bttn.add(add);
        bttn.add(delete);

        name = new JTextField();
        checkOutDate = new JTextField();
        checkInDate = new JTextField();
        email = new JTextField();

        name.setColumns(20);
        checkOutDate.setColumns(20);
        checkInDate.setColumns(20);
        email.setColumns(20);

        txtFlds = new JPanel(new GridLayout(1, 4, 5, 5));

        infoPanel = new JPanel(new GridLayout(0, 1, 2, 2));
        infoPanel.add(txtFldNames);
        infoPanel.add(txtFlds);

        mainPanel = new JPanel(new BorderLayout(5, 5));
        mainPanel.add(infoPanel, BorderLayout.PAGE_START);
        scrollBar = new JScrollPane(mainPanel);
        scrollBar.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

        setTitle("Form 48 Tracker");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setPreferredSize(new Dimension(1000, 400));
        this.add(scrollBar, BorderLayout.CENTER);
        this.add(bttn, BorderLayout.PAGE_END);
        this.pack();
        setLocationRelativeTo(null);
        setVisible(true);

    }

    public void itemStateChanged(ItemEvent checkItem) {
        if (checkItem.getStateChange() == ItemEvent.SELECTED) {
            System.out.println(checkBoxArrLst.size());
        }
        infoPanel.revalidate();
        infoPanel.repaint();
    }

    public static void main(String[] args) {

        new UI();

    }
}