How to get the (x,y) coordinates of JButton

Question

Is there a method to get coordinates in the (x,y) format for a Jbutton similar to the pt.distance() method. The jbutton utilizes setLayout(null) and setBounds(x,y,0,0). How would I compare the results of a pt.distance() and Jbutton(x,y)?

Lastly, how is (x,y) calculated?

 Point pt = evt.getPoint();
    double u = pt.distance((double)x,(double)y);
    double k = st1.getAlignmentX();
    double p = st1.getAlignmentY();
    if(u > ){ // u has to be measured to (x,y) value of jbutton
    tim.setDelay(500);
    }
    if(u < ){
    tim.setDelay(100);
    }

Answer 1

Howabout getLocation, which returns the coordinate of a component on its parent component, or getLocationOnScreen, which returns the coordinate of the component on the display?

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Your second question about how x and y are calculated, I'm not sure what you mean by 'calculated'. The coordinates will be relative to something. Usually either the parent component (like a JPanel on which the JButton is sitting) or a location on the screen (such as getLocation would return for a JFrame).

A method like Point.distance will subtract the two coordinates' x and y values and tell you the difference. This is just basic geometry.

For example, here is a method that will return the distance of a point from the center of a JButton:

public static double getDistance(Point point, JComponent comp) {

    Point loc = comp.getLocation();

    loc.x += comp.getWidth() / 2;
    loc.y += comp.getHeight() / 2;

    double xdif = Math.abs(loc.x - point.x);
    double ydif = Math.abs(loc.y - point.y);

    return Math.sqrt((xdif * xdif) + (ydif * ydif));
}

This returns the hypotenuse of a triangle as a measurement in pixels, which means if the point you give it (like cursor coordinates) is at a diagonal it will give you the useful distance.

Point.distance will do something like this.

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I've noticed this old answer of mine has gotten quite a few views, so here is a better way to do the above (but doesn't really show the math):

public static double distance(Point p, JComponent comp) {
    Point2D.Float center =
        // note: use (0, 0) instead of (getX(), getY())
        // if the Point 'p' is in the coordinates of 'comp'
        // instead of the parent of 'comp'
        new Point2D.Float(comp.getX(), comp.getY());

    center.x += comp.getWidth() / 2f;
    center.y += comp.getHeight() / 2f;

    return center.distance(p);
}

Here's a simple example showing this kind of geometry in a Swing program:

This draws a line to wherever the mouse cursor is and displays the length of the line (which is the distance from the center of the JPanel to the cursor).

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;

class DistanceExample implements Runnable {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new DistanceExample());
    }

    @Override
    public void run() {
        JLabel distanceLabel = new JLabel("--");
        MousePanel clickPanel = new MousePanel();

        Listener listener =
            new Listener(distanceLabel, clickPanel);
        clickPanel.addMouseListener(listener);
        clickPanel.addMouseMotionListener(listener);

        JPanel content = new JPanel(new BorderLayout());
        content.setBackground(Color.white);
        content.add(distanceLabel, BorderLayout.NORTH);
        content.add(clickPanel, BorderLayout.CENTER);

        JFrame frame = new JFrame();
        frame.setContentPane(content);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    static class MousePanel extends JPanel {
        Point2D.Float mousePos;

        MousePanel() {
            setOpaque(false);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);

            if (mousePos != null) {
                g.setColor(Color.red);
                Point2D.Float center = centerOf(this);
                g.drawLine(Math.round(center.x),
                           Math.round(center.y),
                           Math.round(mousePos.x),
                           Math.round(mousePos.y));
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(100, 100);
        }
    }

    static class Listener extends MouseAdapter {
        JLabel distanceLabel;
        MousePanel mousePanel;

        Listener(JLabel distanceLabel, MousePanel mousePanel) {
            this.distanceLabel = distanceLabel;
            this.mousePanel = mousePanel;
        }

        @Override
        public void mouseMoved(MouseEvent e) {
            Point2D.Float mousePos =
                new Point2D.Float(e.getX(), e.getY());

            mousePanel.mousePos = mousePos;
            mousePanel.repaint();

            double dist = distance(mousePos, mousePanel);

            distanceLabel.setText(String.format("%.2f", dist));
        }

        @Override
        public void mouseExited(MouseEvent e) {
            mousePanel.mousePos = null;
            mousePanel.repaint();

            distanceLabel.setText("--");
        }
    }

    static Point2D.Float centerOf(JComponent comp) {
        Point2D.Float center =
            new Point2D.Float((comp.getWidth() / 2f),
                              (comp.getHeight() / 2f));
        return center;
    }

    static double distance(Point2D p, JComponent comp) {
        return centerOf(comp).distance(p);
    }
}