JPanel removeAll不能正常工作

Question

问题：代码中没有包含lPanel.bListPanel.removeAll（）来删除按钮。

我的目标：单击按钮时，我需要旧按钮消失，并需要新的按钮列表填充。

注意：此按钮侦听器与lPanel处于单独的类中。

谢谢！

RoPanel类：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.Border;

public class RoPanel extends JPanel {
    public LPanel lPanel;
    public RPanel rPanel;
    private Ly l;
    private ArrayList<JButton> bButtonList;
    private JTextField newLoadField;
    private JButton theButton;
    public String bText;
    private Border simpleBorder;

  public RoPanel() {
    this.setLayout(new BorderLayout());
    simpleBorder = BorderFactory.createLineBorder(Color.GRAY);
    l = new Ly();
    lPanel = new LPanel();
    rPanel = new RPanel();
    this.setBorder(simpleBorder);
    this.add(lPanel, BorderLayout.WEST);
    this.add(rPanel, BorderLayout.EAST);
    titleBooks = new ArrayList();

    lPanel.getLoadButton();
    lPanel.getLoadButton().addActionListener(new LoadButtonListener());

    newLoadField = lPanel.getLoadField();

    bookButtonList = new ArrayList();
    bookText = new String();
}


private class LoadButtonListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
        String loadStringfile = newLoadField.getText();
        l.loadFromCSV(loadStringfile);

        lPanel.bListPanel.removeAll();

        // for loop that creates buttons
        for (int i = 0; i < l.size(); i++) {
            BButton b = new BButton();

            bButtonList.add(theButton);
            lPanel.bListPanel.add(theButton);
        }

        lPanel.bListPanel.revalidate();
        lPanel.bListPanel.repaint();
    }
  }
}

Lanel类：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.util.ArrayList;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.border.Border;
import javax.swing.border.EtchedBorder;
import javax.swing.border.TitledBorder;
import javax.swing.*;

  public class LPanel extends JPanel {
   private JTextField loadField;
   private JButton loadButton;
   private Border simpleBorder;
   private Border lowerBorder;
   JPanel bListPanel;
   JPanel importPanel;

  public LPanel() {

    this.setLayout(new BorderLayout());
    simpleBorder = BorderFactory.createLineBorder(Color.GRAY);
    lowerBorder = BorderFactory.createEtchedBorder(EtchedBorder.LOWERED);
    bListPanel = new JPanel();
    bListPanel.setLayout(new BoxLayout(bListPanel, BoxLayout.Y_AXIS));
    importPanel = new JPanel();
    this.add(importPanel, BorderLayout.SOUTH);

    // create a jscrollpane that contains all buttons
    JScrollPane scrollPane = new JScrollPane();
    scrollPane.setLocation(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
    scrollPane.getViewport().add(bListPanel);
    this.add(scrollPane);

    // loadfield and load button for iPanel
    loadField = new JTextField();
    loadField.setPreferredSize(new Dimension(170, 25));
    importPanel.add(loadField);
    loadButton = new JButton();
    loadButton.setText("Load");
    importPanel.add(loadButton);
  }
}