拖放后没有GridLayoutManager错误

Question

我正在尝试使用IntelliJ中的Java swing编写程序。我设计了一个带有IntelliJ拖放用户界面的GUI。但是，我的Jlist没有出现在我的Jscrollpane中。 IntelliJ说我的框架没有GridManager，但我尝试添加一个GridManager，它搞砸了我的GUI格式。有人能帮助我吗？谢谢！

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.DefaultListModel;
import javax.swing.GroupLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;

  public class GUIF {

private JButton button5;
private JList list1;
private JButton button1;
private JButton button4;
private JButton button2;
private JButton button3;
private JTextField textField1;
private JPanel Panel;
private JScrollPane scrollpane1;

public GUIF() {


  this.listOps();


  button1.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
      String data = "";
      if (list1.getSelectedIndex() != -1) {
        data = "Item selected: " + list1.getSelectedValue();
        textField1.setText(data);
      }
      textField1.setText(data);
    }
  });
}

private void prepGUI() {
  JFrame frame = new JFrame("Store");
  frame.setContentPane(new GUIF().Panel);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.pack();
  frame.setVisible(true);

}

private void listOps(){
  DefaultListModel<String> items = new DefaultListModel<>();
  items.addElement("chocolate");
  items.addElement("milk");


  list1 = new JList(items);
  list1.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
  list1.setSelectedIndex(0);
  list1.setVisibleRowCount(10);
  list1.setVisible(true);


  scrollpane1.add(list1);

  scrollpane1.setVisible(true);

}

public static void main(String[] args) {
  GUIF guif = new GUIF();
  guif.prepGUI();

}

  }