Polygon (Java)

gistfile1.txt

package Polygon;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.HeadlessException;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;

public class Polygon extends JFrame{

    JButton b1, b2;
    JPanel buttonFrame;
    SpaceFrame spaceFrame;


    public Polygon(String title) throws HeadlessException {
        createButtons();
        this.setTitle("Polygon Drawer");

        buttonFrame = new JPanel();
        buttonFrame.setBackground(Color.BLACK);
        buttonFrame.add(b1);
        buttonFrame.add(b2);
        spaceFrame = new SpaceFrame();
        spaceFrame.addMouseListener(new MouseInnerClassListener());


        this.setLayout(new BorderLayout());
        getContentPane().add(buttonFrame, BorderLayout.NORTH);
        getContentPane().add(spaceFrame, BorderLayout.CENTER);
        this.setSize(300, 300);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.setResizable(false);
    }

    private class MouseInnerClassListener implements MouseListener{

        public MouseInnerClassListener() {
        }

        public void mouseClicked(MouseEvent e) {
        int xPos = e.getX();
        int yPos = e.getY();
        MouseClickPoint mcp = new MouseClickPoint(xPos, yPos);
        spaceFrame.List.add(mcp);
        spaceFrame.draw(xPos, yPos);
    }
        public void mousePressed(MouseEvent e) {
        int xPos = e.getX();
        int yPos = e.getY();
        MouseClickPoint mcp = new MouseClickPoint(xPos, yPos);
        spaceFrame.List.add(mcp);
        spaceFrame.draw(xPos, yPos);
        }

        public void mouseReleased(MouseEvent e) {
        }

        public void mouseEntered(MouseEvent e) {
        }

        public void mouseExited(MouseEvent e) {
        }
    }
    private void createButtons() {
        b1 = new JButton();
        b2 = new JButton();
        b1.addActionListener(new b1Listener());
        b2.addActionListener(new b2Listener());
    }

    class b1Listener implements ActionListener {
        public b1Listener() {
        }
        public void actionPerformed(ActionEvent e) {
            spaceFrame.linkPoints();
        }
    }

    class b2Listener implements ActionListener {
        public b2Listener() {
        }
        public void actionPerformed(ActionEvent e) {
            spaceFrame.clear();
        }
    }

    public static void main(String[] args) {
        Polygon omo = new Polygon("Test");
        omo.setVisible(true);
    }
}

class MouseClickPoint {
    int xPos, yPos;

    MouseClickPoint(int xPos, int yPos) {
        this.xPos = xPos;
        this.yPos = yPos;
    }
}

class SpaceFrame extends JPanel{
    ArrayList<MouseClickPoint> List = new ArrayList<MouseClickPoint>();
    int xPos,yPos;
    boolean lineDrawing = false;

    public SpaceFrame() {
        this.setBackground(Color.LIGHT_GRAY);
    }

    void draw(int x, int y){
        xPos = x;
        yPos = y;
        repaint();
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        if(List.isEmpty()==true){
            return;
        }
        if (!lineDrawing==true) {
            for (int i = 0; i < List.size(); i++) {
                g.fillRect(List.get(i).xPos, List.get(i).yPos, 5, 5);
            }
            g.drawRect(xPos, yPos, 4, 4);

        }
        else{
            for (int i = 1; i < List.size(); i++) {
                g.drawLine(List.get(i).xPos+2, List.get(i).yPos+2, List.get(i-1).xPos+2, List.get(i-1).yPos+2);
            }
            g.drawLine(List.get(List.size()-1).xPos+2, List.get(List.size()-1).yPos+2, List.get(0).xPos+2, List.get(0).yPos+2);
        }
        lineDrawing = false;
    }

    void linkPoints(){
        lineDrawing = true;
        repaint();
    }

    void clear(){
        List.clear();
        repaint();
    }

}