How to move JLabel from one JPanel to another when a button is clicked?

Question

I am a beginner at Java. I was doing this assignment on making a game. I already made the command line program and now I am just trying to make GUI for it. So, the problem I got was: when executing this trial program, Jlabel was not added to p2 panel when a button is clicked. Could you please help me figure out what I did wrong? Thanks.

//imports the necessary packages
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
//GUI controls for Mine Tunnel game, buttons and text fields 
class RiverGUI extends JPanel implements ActionListener {
  private static  boolean gameOver;  
  private JButton clearallButton, wolfButton, goatButton, cabbageButton, resetButton, rowButton;  
  private JTextField msgField;  
  private static RiverCrossing mine;
  private JPanel p, p1,p2,p3,p4,p5;
  private Jlabel wolflabel, goatlabel, cabbagelabel;


 // Constructor creates panels, buttons and other GUI components  
 public RiverGUI() {

    if (mine.flag == true)
        gameOver = true;
    else
         gameOver = false;


    Color topColour, middleColour, bottomColour;   

    mine = new RiverCrossing();   
    topColour = new Color(0,255,0); //creates a variable for color
    middleColour = new Color(0,0,255);
    bottomColour = new Color(0,255,0);

     //Create panels   
     p = new JPanel(new GridLayout(5,1));   
     p1 = new JPanel(); 
     p2 = new JPanel(); 
     p3 = new JPanel();
     p4 = new JPanel();
     p5 = new JPanel(new FlowLayout()); 
     p1.setBackground(topColour);
     p2.setBackground(topColour); 
     p3.setBackground(middleColour); 
     p4.setBackground(bottomColour);
     p5.setBackground(bottomColour); 

     wolflabel = new JLabel("Wolf");
     goatlabel = new JLabel("Goat");
     cabbagelabel = new JLabel("Cabbage");
     wolflabel.setFont(new Font("Serif", Font.BOLD, 24));
     goatlabel.setFont(new Font("Serif", Font.BOLD, 24));
     cabbagelabel.setFont(new Font("Serif", Font.BOLD, 24));

     //***** set background colour for the panels 
     p.setPreferredSize(new Dimension(800,600));
     p1.setPreferredSize(new Dimension(800,50));
     p2.setPreferredSize(new Dimension(800,200));
     p3.setPreferredSize(new Dimension(800,300));
     p4.setPreferredSize(new Dimension(800,200));
     p5.setPreferredSize(new Dimension(800,50));


     p2.setBorder(BorderFactory.createRaisedBevelBorder());
     p3.setBorder(BorderFactory.createRaisedBevelBorder());

     //Create text fields and set properties

     msgField = new JTextField("",30); 

     //Create buttons and set same button size   
     clearallButton = new JButton("clear all");
     wolfButton = new JButton("wolf");
     goatButton = new JButton("goat");
     cabbageButton = new JButton("cabbage");
     resetButton = new JButton("reset");
     rowButton = new JButton("row"); 
     //***** Create other buttons outButton, leftButton, rightButton, resetButton, quitButton 

     //Add components to panels   
     p.add(p1);
     p.add(p2); 
     p.add(p3); 
     p.add(p4);
     p.add(p5);
     p1.add(msgField);
     p1.add(Box.createHorizontalStrut(30));
     p1.add(resetButton);
     p4.add(wolflabel);
     p4.add(Box.createHorizontalStrut(100));
     p4.add(goatlabel);
     p4.add(Box.createHorizontalStrut(100));
     p4.add(cabbagelabel);
     //***** add msgField, counterField, and resetButton buttons to p1 panel   
     p5.add(clearallButton);
     p5.add(Box.createHorizontalStrut(30));
     p5.add(wolfButton);
     p5.add(Box.createHorizontalStrut(30));   
     p5.add(goatButton);
     p5.add(Box.createHorizontalStrut(30));   
     p5.add(cabbageButton);
     p5.add(Box.createHorizontalStrut(30));
     p5.add(rowButton);   
     add(p); //add all GUI components 

     //Add listeners to buttons   
     resetButton.addActionListener(this);
     rowButton.addActionListener(this);
     wolfButton.addActionListener(this);
     goatButton.addActionListener(this);
     cabbageButton.addActionListener(this);
     clearallButton.addActionListener(this);

     //***** add Listener to five other buttons 


    }//end of constructor

    public void actionPerformed(ActionEvent e)  {
       msgField.requestFocus();  
       if (e.getSource() == resetButton) {
         msgField.setText("Game restarted...");

       }

       if (e.getSource() == wolfButton) {
         msgField.setText("You clicked on wolf");
         p2.add(wolflabel);
         p4.remove(wolflabel);


       }
     }  

}