BasicStroke.JOIN_ROUND has the following syntax.
public static final int JOIN_ROUND
In the following code shows how to use BasicStroke.JOIN_ROUND field.
import java.awt.BasicStroke; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.geom.GeneralPath; //from w w w .j av a 2s. com import javax.swing.JFrame; import javax.swing.JPanel; public class Main extends JPanel { public void paint(Graphics g) { Graphics2D g2 = (Graphics2D) g; RenderingHints rh = g2.getRenderingHints(); rh.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2.setRenderingHints(rh); BasicStroke bs = new BasicStroke(36.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_ROUND); g2.setStroke(bs); GeneralPath path = new GeneralPath(); path.moveTo(30.0f, 90.0f); path.lineTo(150.0f, 20.0f); path.lineTo(270.0f, 90.0f); g2.draw(path); } public static void main(String[] args) { JFrame frame = new JFrame(); frame.add(new Main()); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setBounds(20,20, 500,500); frame.setVisible(true); } }