Why does the buttons only appear when I click on them?

Question

So I'm making this drawing program using Java Swing where i can either draw normally or pick a shape and draw that.

This is how it looks like when I start the program

This is after I click on where the buttons are supposed to be

Here are the codes to the program. I'm not sure why the buttons only appear after I click on them. Any ideas?

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.lang.*;

public class DrawProgram extends JFrame implements MouseMotionListener, MouseListener, ChangeListener{
    private Point mousePnt = new Point();
    private Point mousePnt2 = new Point();
    public static Color penColor = new Color(0,0,0);
    private JSlider penSize = new JSlider(JSlider.HORIZONTAL,1,30,4);
    public static int pen = 4;
    private boolean toggle = false;
    private int pointCounter = 1;
    private int shape = 0;
    JToggleButton rectangle;
    JToggleButton circle;
    JToggleButton triangle;
    JToggleButton rhombus;
    
    public DrawProgram(){
    super("Painter");
    JPanel toolbar = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel jp = new JPanel();
        ImageIcon rectangleIcon = new ImageIcon(this.getClass().getResource("/images/rectangle_icon.png"));
        ImageIcon circleIcon = new ImageIcon(this.getClass().getResource("/images/circle_icon.png"));
        ImageIcon triangleIcon = new ImageIcon(this.getClass().getResource("/images/triangle_icon.png"));
        ImageIcon rhombusIcon = new ImageIcon(this.getClass().getResource("/images/rhombus_icon.png"));
        rectangle = new JToggleButton(rectangleIcon);
        circle = new JToggleButton(circleIcon);
        triangle = new JToggleButton(triangleIcon);
        rhombus = new JToggleButton(rhombusIcon);
        
    toolbar.add(new Label("Drag mouse to draw"));
        toolbar.add(penSize);
        toolbar.add(rectangle);
        toolbar.add(circle);
        toolbar.add(triangle);
        toolbar.add(rhombus);
        
    this.add(toolbar,BorderLayout.SOUTH);
        this.add(jp,BorderLayout.CENTER);
        
        rectangle.addItemListener(new rectangleItemListener());
        circle.addItemListener(new circleItemListener());
        triangle.addItemListener(new triangleItemListener());
        rhombus.addItemListener(new rhombusItemListener());
        jp.addMouseMotionListener(this);
        jp.addMouseListener(this);
        penSize.addChangeListener(this);
    setSize(800,600);
    setVisible(true);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    }
    
    public void mouseMoved(MouseEvent me){}
    
    public void mouseDragged(MouseEvent me){
        mousePnt = me.getPoint(); 
        repaint();
    }
    
    public void mouseClicked(MouseEvent me){
        if(me.getModifiers()== MouseEvent.BUTTON3_MASK){              
            penColor = JColorChooser.showDialog(null,"Change pen colour",penColor);
        }
        else if(me.getModifiers()== MouseEvent.BUTTON1_MASK){
            if(toggle == true){
                if(pointCounter == 1){
                    mousePnt = me.getPoint();
                    pointCounter = 2;
                }
                else{
                    mousePnt2 = me.getPoint();
                    pointCounter = 1;
                    repaint();
                }
            }
        }
    }
    
    public void mouseEntered(MouseEvent me){}
    public void mouseExited(MouseEvent me){}
    public void mousePressed(MouseEvent me){}
    public void mouseReleased(MouseEvent me){}

    public void stateChanged(ChangeEvent e){
        JSlider source = (JSlider)e.getSource();
        if(!source.getValueIsAdjusting()){
            pen = (int)source.getValue();
        }    
    }
        
    public void paint(Graphics g){
        g.setColor(penColor);
        
        if(shape == 0)
            g.fillOval(mousePnt.x+8,mousePnt.y+30,pen,pen);
        else if(shape == 1)
            paintRectangle(g);
        else if(shape == 2)
            paintCircle(g);
        else if(shape == 3)
            paintTriangle(g);
        else
            paintRhombus(g);
    }
    
    public void paintRectangle(Graphics g){
        if(mousePnt.x <= mousePnt2.x && mousePnt.y <= mousePnt2.y)  // Up Left Corner
            g.drawRect(mousePnt.x+8, mousePnt.y+30, Math.abs((mousePnt.x+8)-(mousePnt2.x+8)), Math.abs((mousePnt.y+30)-(mousePnt2.y+30)));
        else if(mousePnt.x <= mousePnt2.x && mousePnt.y >= mousePnt2.y) // Down Left Corner
            g.drawRect(mousePnt.x+8, mousePnt2.y+30, Math.abs((mousePnt.x+8)-(mousePnt2.x+8)), Math.abs((mousePnt.y+30)-(mousePnt2.y+30)));
        else if(mousePnt.x >= mousePnt2.x && mousePnt.y <= mousePnt2.y) // Up Right Corner
            g.drawRect(mousePnt2.x+8, mousePnt.y+30, Math.abs((mousePnt.x+8)-(mousePnt2.x+8)), Math.abs((mousePnt.y+30)-(mousePnt2.y+30)));
        else // Down Right Corner
            g.drawRect(mousePnt2.x+8, mousePnt2.y+30, Math.abs((mousePnt.x+8)-(mousePnt2.x+8)), Math.abs((mousePnt.y+30)-(mousePnt2.y+30)));
    }
    
    public void paintCircle(Graphics g){
        if(mousePnt.x <= mousePnt2.x && mousePnt.y <= mousePnt2.y)  // Up Left Corner
            g.drawOval(mousePnt.x+8, mousePnt.y+30, Math.abs((mousePnt.x+8)-(mousePnt2.x+8)), Math.abs((mousePnt.y+30)-(mousePnt2.y+30)));
        else if(mousePnt.x <= mousePnt2.x && mousePnt.y >= mousePnt2.y) // Down Left Corner
            g.drawOval(mousePnt.x+8, mousePnt2.y+30, Math.abs((mousePnt.x+8)-(mousePnt2.x+8)), Math.abs((mousePnt.y+30)-(mousePnt2.y+30)));
        else if(mousePnt.x >= mousePnt2.x && mousePnt.y <= mousePnt2.y) // Up Right Corner
            g.drawOval(mousePnt2.x+8, mousePnt.y+30, Math.abs((mousePnt.x+8)-(mousePnt2.x+8)), Math.abs((mousePnt.y+30)-(mousePnt2.y+30)));
        else // Down Right Corner
            g.drawOval(mousePnt2.x+8, mousePnt2.y+30, Math.abs((mousePnt.x+8)-(mousePnt2.x+8)), Math.abs((mousePnt.y+30)-(mousePnt2.y+30)));
    }
    
    public void paintTriangle(Graphics g){
        if(mousePnt.y <= mousePnt2.y){
            g.drawLine(mousePnt.x+8,mousePnt2.y+30,mousePnt2.x+8,mousePnt2.y+30);
            g.drawLine(mousePnt.x+8,mousePnt2.y+30,(mousePnt.x+8+mousePnt2.x+8)/2,mousePnt.y+30);
            g.drawLine(mousePnt2.x+8,mousePnt2.y+30,(mousePnt.x+8+mousePnt2.x+8)/2,mousePnt.y+30);
        }
        else{
            g.drawLine(mousePnt.x+8,mousePnt.y+30,mousePnt2.x+8,mousePnt.y+30);
            g.drawLine(mousePnt.x+8,mousePnt.y+30,(mousePnt.x+8+mousePnt2.x+8)/2,mousePnt2.y+30);
            g.drawLine(mousePnt2.x+8,mousePnt.y+30,(mousePnt.x+8+mousePnt2.x+8)/2,mousePnt2.y+30);
        }
    }
    
    public void paintRhombus(Graphics g){
        g.drawLine((mousePnt.x+8+mousePnt2.x+8)/2,mousePnt.y+30,mousePnt.x+8,(mousePnt.y+30+mousePnt2.y+30)/2);
        g.drawLine((mousePnt.x+8+mousePnt2.x+8)/2,mousePnt.y+30,mousePnt2.x+8,(mousePnt.y+30+mousePnt2.y+30)/2);
        g.drawLine((mousePnt.x+8+mousePnt2.x+8)/2,mousePnt2.y+30,mousePnt.x+8,(mousePnt.y+30+mousePnt2.y+30)/2);
        g.drawLine((mousePnt.x+8+mousePnt2.x+8)/2,mousePnt2.y+30,mousePnt2.x+8,(mousePnt.y+30+mousePnt2.y+30)/2);
    }
    
    public class rectangleItemListener implements ItemListener{
        public void itemStateChanged(ItemEvent eve){
            if(rectangle.isSelected()){
                toggle = true;
                shape = 1;
            }
            else{
                toggle = false;
                shape = 0;
            }
        }
    }
    
    public class circleItemListener implements ItemListener{
        public void itemStateChanged(ItemEvent eve){
            if(circle.isSelected()){
                toggle = true;
                shape = 2;
            }
            else{
                toggle = false;
                shape = 0;
            }
        }
    }
    
    public class triangleItemListener implements ItemListener{
        public void itemStateChanged(ItemEvent eve){
            if(triangle.isSelected()){
                toggle = true;
                shape = 3;
            }
            else{
                toggle = false;
                shape = 0;
            }
        }
    }
    
    public class rhombusItemListener implements ItemListener{
        public void itemStateChanged(ItemEvent eve){
            if(rhombus.isSelected()){
                toggle = true;
                shape = 4;
            }
            else{
                toggle = false;
                shape = 0;
            }
        }
    }

    public static void main(String[] a){
    new DrawProgram();
    }
}