How should I split joined lines for my paint app in java

Question

I am new to using paint and lines in java, sorry if the answer is obvious. Never the less I would like to have my lines smooth and that is why I have the "Circles" join as to make a line with rounded corners, the problem is it doesn't recognize when the mouse is released so when I try to write another letter it connects the two points across the scree. What is the best way to program my application to have smooth lines with out being connected?

package pac;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.geom.Line2D;
import java.util.ArrayList;

import javax.swing.*;

public class Frame extends JPanel{

    private final ArrayList<Point> point = new ArrayList<>();

    public Frame() {
        addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent event) {
                point.add(event.getPoint());
                repaint();
            }
        });

        addMouseMotionListener(new MouseMotionAdapter() {
        public void mouseDragged(MouseEvent event) {
            point.add(event.getPoint());
            repaint();
        }
    });
}

public void paintComponent(Graphics g) {
    super.paintComponents(g);
    Graphics2D g2 = (Graphics2D) g;
    g2.setColor(new Color(0, 0, 128));
    g2.setStroke(new BasicStroke(15f,
                                 BasicStroke.CAP_ROUND,
                                 BasicStroke.JOIN_ROUND));
 //   if(!mouserelased) {
        for (int i = 1; i < point.size(); i++)
            g2.draw(new Line2D.Float(point.get(i-1), point.get(i)));
 //   }
    }

public static void main(String[] args) {
    JFrame f = new JFrame();
    f.add(new Frame());
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setSize(800, 600);
    f.setVisible(true);
}
}