ArrayList to Array without affecting my program[functional] JAVA

Simple question yet somewhat complex for me to get it working. I want to get rid of my arraylist because I'm not suppose to use arraylist in my project. Background about my app, it's a polymorphic app with components(shapes) that once its own button is clicked they show on the screen on on top of the other. Hard to explain. I will post a picture of it along with the area where the arraylist is located(piece of the code). The program is fully functional. Thanks again.

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


public class ShapeDraw{   
public static void main(String[] args){
	JFrame frame = new JFrame("My Moving Shapes");
	Container contentPane=frame.getContentPane();
	contentPane.add(new MyCanvas());
	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	frame.pack();
	frame.setVisible(true);
   }
}
@SuppressWarnings("serial")
class MyCanvas extends JPanel implements ActionListener, MouseListener, MouseMotionListener {
      ArrayList<MyShape> shapes = new ArrayList<MyShape>(); 
      Color currentColor = Color.blue;   
	 public MyCanvas() {	    
		 setPreferredSize(new Dimension(400, 300));
		 JComboBox<String> colorOption = new JComboBox<String>();
		 colorOption.addItem("Blue");
		 colorOption.addItem("Magenta");
		 colorOption.addItem("Red");
		 colorOption.addActionListener(this);

		 JButton rectButton = new JButton("Rect");
		 rectButton.addActionListener(this);

		 JButton ovalButton = new JButton("Oval");
		 ovalButton.addActionListener(this);

		 JButton roundRectButton = new JButton("RoundRect");
		 roundRectButton.addActionListener(this);

		 JPanel bottom = new JPanel();   // a Panel to hold the control buttons
		 bottom.setLayout(new GridLayout(1,4,3,3));
		 bottom.add(rectButton);
		 bottom.add(ovalButton);
		 bottom.add(roundRectButton);
		 bottom.add(colorOption);

		 setLayout(new BorderLayout(3,3));             
		 add("South",bottom);
		 addMouseListener(this);
         addMouseMotionListener(this);
		 setBackground(Color.gray);
      }   
	   
      public void paintComponent(Graphics g) {
         g.setColor(getBackground());
         g.fillRect(0,0,getSize().width,getSize().height);
         int top = shapes.size();
         for (int i = 0; i < top; i++) {
            MyShape s = (MyShape)shapes.get(i);
            s.draw(g);
         }
      }   

      public void actionPerformed(ActionEvent evt) {
         if (evt.getSource() instanceof JComboBox) {
            switch ( ((JComboBox<?>)evt.getSource()).getSelectedIndex() ) {
               case 0: currentColor = Color.blue;     break;
               case 1: currentColor = Color.magenta;   break;
               case 2: currentColor = Color.red;    break;
            }
         }
         else {
            String command = evt.getActionCommand();
            if (command.equals("Rect"))
               addShape(new RectShape());
            else if (command.equals("Oval"))
               addShape(new OvalShape());
            else if (command.equals("RoundRect"))
               addShape(new RoundRectShape());
            }
      }