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    <p>Ok, pick a point on the screen of your application. Say, the center. mark that point as the anchor. </p> <p>Now, add a <code>MouseMotionListener</code> to your screen and look for whenever the mouse is moved. You need this point to draw a line. The first point being the anchor.<br> Now, call <code>repaint()</code> every time the mouse moves. </p> <p>In the <code>paintComponent(Graphics g)</code> , use the <code>g.drawLine(anchorX,anchorY,mouseX,mouseY)</code> to draw the line. Since <code>paint()</code> is called before <code>repaint()</code>, you need to give some initial value to these 4 variables. </p> <p><strong>SSCCE:</strong> </p> <pre><code> import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Toolkit; import java.awt.event.MouseEvent; import java.awt.event.MouseMotionListener; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.SwingUtilities; public class LineFollower extends JFrame{ int anchorX = 0; int anchorY = 0; int mouseX = 0; int mouseY = 0; JPanel canvas = new JPanel(){ @Override public Dimension getPreferredSize() { return new Dimension(500, 500); } @Override public void paintComponent(Graphics g){ super.paintComponent(); g.setColor(Color.RED); g.drawLine(anchorX, anchorY, mouseX, mouseY); } }; public LineFollower(){ anchorX = 500 / 2; anchorY = 500 / 2; this.getContentPane().add(canvas); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); canvas.addMouseMotionListener(new MouseMotionListener(){ @Override public void mouseDragged(MouseEvent e) { mouseX = e.getX(); mouseY = e.getY(); repaint(); } @Override public void mouseMoved(MouseEvent e) { mouseX = e.getX(); mouseY = e.getY(); repaint(); } }); this.pack(); //this.setSize(500,500); this.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable(){ @Override public void run() { new LineFollower(); } }); } } </code></pre>
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    1. POMake a line point towards the mouse
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    1. COI already have a mouselistener though
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    2. CO@Cj1m Then all you need to do is use my method :) Much simpler, no trigonometry.
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    3. COThat doesn't work either, it gives the same results as the code before.
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