我想为我的项目学习一些有关 JAVA 的技巧。
我想从左到右、从右到左对我的矩形进行动画处理，但我无法对球动画应用相同的功能。
另外，如何以 y 坐标边框在不同的 x 方向上启动我的球？
非常感谢您的建议和帮助。
我的代码：
import javax.swing.Timer;
import java.util.ArrayList;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class MultipleBall extends JApplet {
public MultipleBall() {
add(new BallControl());
}
class BallControl extends JPanel {
private BallPanel ballPanel = new BallPanel();
private JButton Suspend = new JButton("Suspend");
private JButton Resume = new JButton("Resume");
private JButton Add = new JButton("+1");
private JButton Subtract = new JButton("-1");
private JScrollBar Delay = new JScrollBar();
public BallControl() {
// Group buttons in a panel
JPanel panel = new JPanel();
panel.add(Suspend);
panel.add(Resume);
panel.add(Add);
panel.add(Subtract);
// Add ball and buttons to the panel
ballPanel.setBorder(new javax.swing.border.LineBorder(Color.red));
Delay.setOrientation(JScrollBar.HORIZONTAL);
ballPanel.setDelay(Delay.getMaximum());
setLayout(new BorderLayout());
add(Delay, BorderLayout.NORTH);
add(ballPanel, BorderLayout.CENTER);
add(panel, BorderLayout.SOUTH);
// Register listeners
Suspend.addActionListener(new Listener());
Resume.addActionListener(new Listener());
Add.addActionListener(new Listener());
Subtract.addActionListener(new Listener());
Delay.addAdjustmentListener(new AdjustmentListener() {
public void adjustmentValueChanged(AdjustmentEvent e) {
ballPanel.setDelay(Delay.getMaximum() - e.getValue());
}
});
}
class Listener implements ActionListener {
public void actionPerformed(ActionEvent e) {
if (e.getSource() == Suspend)
ballPanel.suspend();
else if (e.getSource() == Resume)
ballPanel.resume();
else if (e.getSource() == Add)
ballPanel.add();
else if (e.getSource() == Subtract)
ballPanel.subtract();
}
}
}
class BallPanel extends JPanel {
private int delay = 30;
private ArrayList<Ball> list = new ArrayList<Ball>();
// Create a timer with the initial delay
protected Timer timer = new Timer(delay, new ActionListener() {
/** Handle the action event */
public void actionPerformed(ActionEvent e) {
repaint();
}
});
public BallPanel() {
timer.start();
}
public void add() {
list.add(new Ball());
}
public void subtract() {
if (list.size() > 0)
list.remove(list.size() - 1); // Remove the last ball
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(185, 279, 50, 15);
g.setColor(Color.RED);
g.fillRect(185, 279, 50, 15);
for (int i = 0; i < list.size(); i++) {
Ball ball = (Ball) list.get(i); // Get a ball
g.setColor(ball.color); // Set ball color
// Check boundaries
if (ball.x < 0 || ball.x > getWidth())
ball.dx = -ball.dx;
if (ball.y < 0 || ball.y > getHeight())
ball.dy = -ball.dy;
// Adjust ball position
ball.x += ball.dx;
// ball.y += ball.dy;
g.fillOval(ball.x - ball.radius, ball.y - ball.radius,
ball.radius * 2, ball.radius * 2);
}
}
public void suspend() {
timer.stop();
}
public void resume() {
timer.start();
}
public void setDelay(int delay) {
this.delay = delay;
timer.setDelay(delay);
}
}
class Ball {
int x = 20;
int y = 20; // Current ball position
int dx = 2; // Increment on ball's x-coordinate
int dy = 2; // Increment on ball's y-coordinate
int radius = 15; // Ball radius
Color color = new Color((int) (Math.random() * 256),
(int) (Math.random() * 256), (int) (Math.random() * 256));
}
/** Main method */
public static void main(String[] args) {
JFrame frame = new JFrame();
JApplet applet = new MultipleBallApp();
frame.add(applet);
frame.setTitle("MultipleBallApp");
frame.setLocationRelativeTo(null); // Center the frame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 400);
frame.setLocationRelativeTo(null); // Center the frame
frame.setVisible(true);
}
}
无法对球动画应用相同的功能
这可能是你的第一个错误。事实上，这正是您应该尝试做的。这个想法是，您应该尝试设计一种方法，通过绘制/动画的内容是抽象的，因此无论您想要绘制什么形状，您都可以将其应用到相同的基本动画过程中......
例如，你可以从某种开始interface它描述了动画实体的基本属性......
public interface AnimatedShape {
public void update(Rectangle bounds);
public void paint(JComponent parent, Graphics2D g2d);
}
这表示动画实体可以更新（移动）和绘制。按照惯例（而且因为我很懒），我喜欢创建一个abstract实现最常见方面的实现......
public abstract class AbstractAnimatedShape implements AnimatedShape {
private Rectangle bounds;
private int dx, dy;
public AbstractAnimatedShape() {
}
public void setBounds(Rectangle bounds) {
this.bounds = bounds;
}
public Rectangle getBounds() {
return bounds;
}
public int getDx() {
return dx;
}
public int getDy() {
return dy;
}
public void setDx(int dx) {
this.dx = dx;
}
public void setDy(int dy) {
this.dy = dy;
}
@Override
public void update(Rectangle parentBounds) {
Rectangle bounds = getBounds();
int dx = getDx();
int dy = getDy();
bounds.x += dx;
bounds.y += dy;
if (bounds.x < parentBounds.x) {
bounds.x = parentBounds.x;
setDx(dx *= -1);
} else if (bounds.x + bounds.width > parentBounds.x + parentBounds.width) {
bounds.x = parentBounds.x + (parentBounds.width - bounds.width);
setDx(dx *= -1);
}
if (bounds.y < parentBounds.y) {
bounds.y = parentBounds.y;
setDy(dy *= -1);
} else if (bounds.y + bounds.height > parentBounds.y + parentBounds.height) {
bounds.y = parentBounds.y + (parentBounds.height - bounds.height);
setDy(dy *= -1);
}
}
}
然后开始创建实现......
public class AnimatedBall extends AbstractAnimatedShape {
private Color color;
public AnimatedBall(int x, int y, int radius, Color color) {
setBounds(new Rectangle(x, y, radius * 2, radius * 2));
this.color = color;
setDx(Math.random() > 0.5 ? 2 : -2);
setDy(Math.random() > 0.5 ? 2 : -2);
}
public Color getColor() {
return color;
}
@Override
public void paint(JComponent parent, Graphics2D g2d) {
Rectangle bounds = getBounds();
g2d.setColor(getColor());
g2d.fillOval(bounds.x, bounds.y, bounds.width, bounds.height);
}
}
通过这种方式，您可以自定义实体的动画和绘制方式，但实体的每个实例的基本逻辑是相同的......
但这有什么意义呢...
基本上，它允许我们做的是产生所有动画对象的“虚拟”概念并简化管理，例如......
而不是使用“紧密”耦合List，我们可以使用一对松散的List反而...
private ArrayList<AnimatedShape> list = new ArrayList<AnimatedShape>();
然后当我们想要更新实体时，我们只需要迭代List并要求实体更新...
protected Timer timer = new Timer(delay, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
for (AnimatedShape ball : list) {
ball.update(getBounds());
}
repaint();
}
});
当它们需要被涂漆时......
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (AnimatedShape ball : list) {
ball.paint(this, g2d);
}
}
因为BallPane不关心它实际上是什么类型的实体，而只关心它是一种类型AnimatedShape...让生活更轻松...
现在，我的实现AnimatedBall已经随机化了球的每个实例的方向，但是您也可以使用以下内容随机化添加球时的起始位置......
public void add() {
int radius = 15;
// Randomised position
int x = (int)(Math.random() * (getWidth() - (radius * 2))) + radius;
int y = (int)(Math.random() * (getHeight() - (radius * 2))) + radius;
Color color = new Color((int) (Math.random() * 256),
(int) (Math.random() * 256), (int) (Math.random() * 256));
AnimatedBall ball = new AnimatedBall(x, y, radius, color);
list.add(ball);
}
但这如何帮助您添加矩形呢？
您现在需要创建一个AnimatedRectangle延伸自AbstractAnimatedShape并实现了所需的方法并将其实例添加到List of AnimatedShape是在BallPane.
如果您不希望在同一列表中管理矩形，您可以创建另一个列表并单独管理它（它创建两个附加方法，update(List<AnimatedShape>) and paint(List<AnimatedShape>, Graphics2D)传递每个单独的列表以减少重复的代码，但这就是我）...
您可以通过覆盖来限制矩形的垂直移动setDy方法并忽略任何更改，例如
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MultipleBall {
public MultipleBall() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("MultipleBallApp");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new BallControl());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class BallControl extends JPanel {
private BallPanel ballPanel = new BallPanel();
private JButton Suspend = new JButton("Suspend");
private JButton Resume = new JButton("Resume");
private JButton Add = new JButton("+1");
private JButton Subtract = new JButton("-1");
private JScrollBar Delay = new JScrollBar();
public BallControl() {
// Group buttons in a panel
JPanel panel = new JPanel();
panel.add(Suspend);
panel.add(Resume);
panel.add(Add);
panel.add(Subtract);
// Add ball and buttons to the panel
ballPanel.setBorder(new javax.swing.border.LineBorder(Color.red));
Delay.setOrientation(JScrollBar.HORIZONTAL);
ballPanel.setDelay(Delay.getMaximum());
setLayout(new BorderLayout());
add(Delay, BorderLayout.NORTH);
add(ballPanel, BorderLayout.CENTER);
add(panel, BorderLayout.SOUTH);
// Register listeners
Suspend.addActionListener(new Listener());
Resume.addActionListener(new Listener());
Add.addActionListener(new Listener());
Subtract.addActionListener(new Listener());
Delay.addAdjustmentListener(new AdjustmentListener() {
public void adjustmentValueChanged(AdjustmentEvent e) {
ballPanel.setDelay(Delay.getMaximum() - e.getValue());
}
});
}
class Listener implements ActionListener {
public void actionPerformed(ActionEvent e) {
if (e.getSource() == Suspend) {
ballPanel.suspend();
} else if (e.getSource() == Resume) {
ballPanel.resume();
} else if (e.getSource() == Add) {
ballPanel.add();
} else if (e.getSource() == Subtract) {
ballPanel.subtract();
}
}
}
}
class BallPanel extends JPanel {
private int delay = 30;
private ArrayList<AnimatedShape> list = new ArrayList<AnimatedShape>();
private AnimatedRectange rectangle;
public BallPanel() {
this.rectangle = new AnimatedRectange(-25, 200, 50, 25, Color.RED);
timer.start();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
// Create a timer with the initial delay
protected Timer timer = new Timer(delay, new ActionListener() {
/**
* Handle the action event
*/
@Override
public void actionPerformed(ActionEvent e) {
for (AnimatedShape ball : list) {
ball.update(getBounds());
}
rectangle.update(getBounds());
repaint();
}
});
public void add() {
int radius = 15;
// Randomised position
int x = (int) (Math.random() * (getWidth() - (radius * 2))) + radius;
int y = (int) (Math.random() * (getHeight() - (radius * 2))) + radius;
Color color = new Color((int) (Math.random() * 256),
(int) (Math.random() * 256), (int) (Math.random() * 256));
AnimatedBall ball = new AnimatedBall(x, y, radius, color);
list.add(ball);
}
public void subtract() {
if (list.size() > 0) {
list.remove(list.size() - 1); // Remove the last ball
}
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (AnimatedShape ball : list) {
ball.paint(this, g2d);
}
rectangle.paint(this, g2d);
}
public void suspend() {
timer.stop();
}
public void resume() {
timer.start();
}
public void setDelay(int delay) {
this.delay = delay;
timer.setDelay(delay);
}
}
public interface AnimatedShape {
public void update(Rectangle bounds);
public void paint(JComponent parent, Graphics2D g2d);
}
public abstract class AbstractAnimatedShape implements AnimatedShape {
private Rectangle bounds;
private int dx, dy;
public AbstractAnimatedShape() {
}
public void setBounds(Rectangle bounds) {
this.bounds = bounds;
}
public Rectangle getBounds() {
return bounds;
}
public int getDx() {
return dx;
}
public int getDy() {
return dy;
}
public void setDx(int dx) {
this.dx = dx;
}
public void setDy(int dy) {
this.dy = dy;
}
@Override
public void update(Rectangle parentBounds) {
Rectangle bounds = getBounds();
int dx = getDx();
int dy = getDy();
bounds.x += dx;
bounds.y += dy;
if (bounds.x < parentBounds.x) {
bounds.x = parentBounds.x;
setDx(dx *= -1);
} else if (bounds.x + bounds.width > parentBounds.x + parentBounds.width) {
bounds.x = parentBounds.x + (parentBounds.width - bounds.width);
setDx(dx *= -1);
}
if (bounds.y < parentBounds.y) {
bounds.y = parentBounds.y;
setDy(dy *= -1);
} else if (bounds.y + bounds.height > parentBounds.y + parentBounds.height) {
bounds.y = parentBounds.y + (parentBounds.height - bounds.height);
setDy(dy *= -1);
}
}
}
public class AnimatedBall extends AbstractAnimatedShape {
private Color color;
public AnimatedBall(int x, int y, int radius, Color color) {
setBounds(new Rectangle(x, y, radius * 2, radius * 2));
this.color = color;
setDx(Math.random() > 0.5 ? 2 : -2);
setDy(Math.random() > 0.5 ? 2 : -2);
}
public Color getColor() {
return color;
}
@Override
public void paint(JComponent parent, Graphics2D g2d) {
Rectangle bounds = getBounds();
g2d.setColor(getColor());
g2d.fillOval(bounds.x, bounds.y, bounds.width, bounds.height);
}
}
public class AnimatedRectange extends AbstractAnimatedShape {
private Color color;
public AnimatedRectange(int x, int y, int width, int height, Color color) {
setBounds(new Rectangle(x, y, width, height));
this.color = color;
setDx(2);
}
// Don't want to adjust the vertical speed
@Override
public void setDy(int dy) {
}
@Override
public void paint(JComponent parent, Graphics2D g2d) {
Rectangle bounds = getBounds();
g2d.setColor(color);
g2d.fill(bounds);
}
}
/**
* Main method
*/
public static void main(String[] args) {
new MultipleBall();
}
}
修正案
JApplet to a JFrame，一个小程序有一个规定的生命周期和管理流程，而你却忽略了。最好只专注于使用BallControlpanel 作为核心 UI 元素，然后将其添加到您想要的顶级容器中JScrollBar更不用说，它在不同平台上看起来会更好，大多数用户都了解滑块的用途......