Drawing a line with arrow in Java

Question

Can anyone guide me how to code the arrow line in different direction. wa and wl is positive the rectangle

Answer 1

Here is a simple routine (adopted from here) for drawing arbitrary arrows:

import static java.awt.geom.AffineTransform.*;
import java.awt.*;
import java.awt.geom.AffineTransform;
import javax.swing.*;

public class Main {
    public static void main(String args[]) {
        JFrame t = new JFrame();
        t.add(new JComponent() {

            private final int ARR_SIZE = 4;

            void drawArrow(Graphics g1, int x1, int y1, int x2, int y2) {
                Graphics2D g = (Graphics2D) g1.create();

                double dx = x2 - x1, dy = y2 - y1;
                double angle = Math.atan2(dy, dx);
                int len = (int) Math.sqrt(dx*dx + dy*dy);
                AffineTransform at = AffineTransform.getTranslateInstance(x1, y1);
                at.concatenate(AffineTransform.getRotateInstance(angle));
                g.transform(at);

                // Draw horizontal arrow starting in (0, 0)
                g.drawLine(0, 0, len, 0);
                g.fillPolygon(new int[] {len, len-ARR_SIZE, len-ARR_SIZE, len},
                              new int[] {0, -ARR_SIZE, ARR_SIZE, 0}, 4);
            }

            public void paintComponent(Graphics g) {
                for (int x = 15; x < 200; x += 16)
                    drawArrow(g, x, x, x, 150);
                drawArrow(g, 30, 300, 300, 190);
            }
        });

        t.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        t.setSize(400, 400);
        t.setVisible(true);
    }
}

Result:

Answer 2

Simple arrow sample

/**
 * @param fromPoint end of the arrow
 * @param rotationDeg rotation angle of line
 * @param length arrow length
 * @param wingsAngleDeg wingspan of arrow
 * @return Path2D arrow shape
 */
public static Path2D createArrowForLine(
                 Point2D fromPoint, 
                 double rotationDeg, 
                 double length, 
                 double wingsAngleDeg) {

        double ax = fromPoint.getX();
        double ay = fromPoint.getY();

        double radB = Math.toRadians(-rotationDeg + wingsAngleDeg);
        double radC = Math.toRadians(-rotationDeg - wingsAngleDeg);

        Path2D resultPath = new Path2D.Double();
        resultPath.moveTo(length * Math.cos(radB) + ax, length * Math.sin(radB) + ay);
        resultPath.lineTo(ax, ay);
        resultPath.lineTo(length * Math.cos(radC) + ax, length * Math.sin(radC) + ay);
        return resultPath;
    }