您可能希望嵌套列表以实现您的目标：
List<List<Point>>
这样，当按下鼠标时，启动一个ArrayList，并在释放时
完成它。然后，您可以使用嵌套的for循环绘制所有曲线。
例如（来自我之前的答案）：
import java.awt.BasicStroke;import java.awt.Color;import java.awt.Dimension;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.GridLayout;import java.awt.Point;import java.awt.event.MouseAdapter;import java.awt.event.MouseEvent;import java.util.ArrayList;import java.util.List;import javax.swing.*;import javax.swing.border.Border;import javax.swing.border.TitledBorder;public class LineDrawEg { private static void createAndShowGui() { JPanel mainPanel = new JPanel(new GridLayout(1, 0)); mainPanel.setPreferredSize(new Dimension(800, 400)); MyMouseAdapter mouseAdapter = new MyMouseAdapter(); JPanel[] panels = {new Panel1(), new Panel2()}; for (int i = 0; i < panels.length; i++) { String title = "Panel " + (i + 1); Border border = new TitledBorder(title); panels[i].setBorder(border); panels[i].addMouseListener(mouseAdapter); panels[i].addMouseMotionListener(mouseAdapter); mainPanel.add(panels[i]); } Jframe frame = new Jframe("Line Draw Eg"); frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); frame.getContentPane().add(mainPanel); frame.pack(); frame.setLocationByPlatform(true); frame.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGui(); } }); }}class Panel1 extends JPanel implements Positionable { private int xPos = 0; private int yPos = 0; @Override protected void paintComponent(Graphics g) { // super.paintComponent(g); g.setColor(Color.red); g.fillOval(xPos, yPos, 5, 5); } @Override public void mouseDragged(Point p) { xPos = p.x; yPos = p.y; repaint(); } @Override public void mousePressed(Point p) { xPos = p.x; yPos = p.y; repaint(); } @Override public void mouseReleased(Point p) { xPos = p.x; yPos = p.y; repaint(); }}class Panel2 extends JPanel implements Positionable { private List<List<Point>> listOfLists = new ArrayList<List<Point>>(); private List<Point> currentPoints; @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D) g; g2.setStroke(new BasicStroke(5f)); if (currentPoints != null && currentPoints.size() > 1) { g2.setColor(Color.blue); for (int i = 1; i < currentPoints.size(); i++) { int x1 = currentPoints.get(i - 1).x; int y1 = currentPoints.get(i - 1).y; int x2 = currentPoints.get(i).x; int y2 = currentPoints.get(i).y; g2.drawLine(x1, y1, x2, y2); } } g2.setColor(Color.red); for (List<Point> pointList : listOfLists) { if (pointList.size() > 1) { for (int i = 1; i < pointList.size(); i++) { int x1 = pointList.get(i - 1).x; int y1 = pointList.get(i - 1).y; int x2 = pointList.get(i).x; int y2 = pointList.get(i).y; g2.drawLine(x1, y1, x2, y2); } } } } @Override public void mousePressed(Point p) { currentPoints = new ArrayList<Point>(); currentPoints.add(p); repaint(); } @Override public void mouseDragged(Point p) { currentPoints.add(p); repaint(); } @Override public void mouseReleased(Point p) { if (currentPoints != null) { currentPoints.add(p); listOfLists.add(currentPoints); } currentPoints = null; repaint(); }}class MyMouseAdapter extends MouseAdapter { @Override public void mouseDragged(MouseEvent mEvt) { Positionable positionable = (Positionable) mEvt.getSource(); positionable.mouseDragged(mEvt.getPoint()); } @Override public void mousePressed(MouseEvent mEvt) { Positionable positionable = (Positionable) mEvt.getSource(); positionable.mousePressed(mEvt.getPoint()); } @Override public void mouseReleased(MouseEvent mEvt) { Positionable positionable = (Positionable) mEvt.getSource(); positionable.mouseReleased(mEvt.getPoint()); }}interface Positionable { void mouseDragged(Point p); void mousePressed(Point p); void mouseReleased(Point p);}
