因此，通过浏览JavaDocs
for
Ellipse2D很显然，
Ellipse2D它不会公开公开
x/
y属性。
相反，您必须改用其中一种
setframe方法。
此示例是对示例的稍作修改，该示例决定了
mousePressed事件发生时应移动哪个椭圆，因为在我看来，在
mouseDragged事件内进行此操作没有任何意义，除非您希望接听所有的椭圆。它还在“点击”点和椭圆的位置之间定义了一个偏移量，以使它们不会“跳转”到鼠标的位置。
import java.awt.Color;import java.awt.Container;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.Shape;import java.awt.event.MouseEvent;import java.awt.event.MouseListener;import java.awt.event.MouseMotionListener;import java.awt.geom.Ellipse2D;import java.awt.geom.Point2D;import java.awt.geom.Rectangle2D;import java.util.ArrayList;import java.util.List;import javax.swing.Jframe;import javax.swing.JPanel;public class Sample extends Jframe implements MouseListener, MouseMotionListener { JPanel MainPane; Container contentPane; ArrayList<Ellipse2D> redEl = new ArrayList<Ellipse2D>(); ArrayList<Ellipse2D> whiteEl = new ArrayList<Ellipse2D>(); Ellipse2D el1 = new Ellipse2D.Double(120, 110, 50, 50); Ellipse2D el2 = new Ellipse2D.Double(250, 110, 50, 50); Ellipse2D el3 = new Ellipse2D.Double(390, 110, 50, 50); Ellipse2D el4 = new Ellipse2D.Double(540, 110, 50, 50); Ellipse2D el5 = new Ellipse2D.Double(120, 390, 50, 50); Ellipse2D el6 = new Ellipse2D.Double(250, 390, 50, 50); Ellipse2D el7 = new Ellipse2D.Double(390, 390, 50, 50); Ellipse2D el8 = new Ellipse2D.Double(540, 390, 50, 50); int x; int y; private Point2D.Double offSet; public Sample() { redEl.add(el1); redEl.add(el2); redEl.add(el3); redEl.add(el4); whiteEl.add(el5); whiteEl.add(el6); whiteEl.add(el7); whiteEl.add(el8); MainPane = new JPanel() { public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D) g; for (Shape red : redEl) { g2.setColor(Color.RED); g2.fill(red); g2.draw(red); } for (Shape white : whiteEl) { g2.setColor(Color.WHITE); g2.fill(white); g2.draw(white); } } }; MainPane.setBackground(Color.BLACK); contentPane = this.getContentPane(); contentPane.add(MainPane); MainPane.setLayout(null); setVisible(true); setSize(701, 701); setResizable(false); setLocationRelativeTo(null); setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); MainPane.addMouseListener(this); MainPane.addMouseMotionListener(this); } private Ellipse2D selected = null; public void mousePressed(MouseEvent e) { x = e.getX(); y = e.getY(); List<Ellipse2D> all = new ArrayList<>(redEl); all.addAll(whiteEl); for (Ellipse2D el : all) { if (el.contains(x, y)) { selected = el; offSet = new Point2D.Double(x - el.getX(), y - el.getY()); break; } } } public void mouseClicked(MouseEvent e) { selected = null; } public void mouseReleased(MouseEvent e) { } public void mouseEntered(MouseEvent e) { } public void mouseExited(MouseEvent e) { } public void mouseDragged(MouseEvent e) { if (selected != null) { double x = e.getX() - offSet.x; double y = e.getY() - offSet.y; Rectangle2D bounds = selected.getBounds2D(); bounds.setframe(new Rectangle2D.Double(x, y, bounds.getWidth(), bounds.getHeight())); selected.setframe(bounds); repaint(); } } public void mouseMoved(MouseEvent e) { } public static void main(String args[]) { new Sample(); }}
