我正在玩awt图形，起初我设法按照我想要的方式获取了所有内容，但是在清理了我的代码后，突然里面除了JPanel之外没有空框架出现了。
这可能很痛苦，但是我找不到为什么我的形状不再出现的原因了。我在做什么错了？
public class Main {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Game().setVisible(true);
}
});
}
}
public class Game extends JFrame {
static int width = 500;
static int height = 500;
public Game() {
this.setPreferredSize(new Dimension(width, height));
JPanel menuPanel = new JPanel(); // Menypanel
JPanel filmPanel = new JPanel(); // Filmpanel
JPanel gamePanel = new JPanel(); // Spelpanel
gamePanel.setBackground(Color.WHITE);
// Intro texts
Queue<String> intro = new ArrayDeque<>();
intro.add("Welcome to the jungle!");
intro.add("We've got fun and games.");
FadingTextBox introBox = new FadingTextBox(intro);
gamePanel.add(introBox);
getContentPane().add(gamePanel);
setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
pack();
}
}
这个根本没有出现：
class FadingTextBox extends JComponent implements ActionListener {
private RoundRectangle2D rr;
private String text = "";
private float alpha;
private float alphaDelta = 0.05f; // Alpha fade speed
private final int fps = 60; // FPS
private javax.swing.Timer timer = new Timer(1000 / fps, this);
private java.util.Queue<String> textQueue; // Contains lines of texts
public FadingTextBox(java.util.Queue<String> textQueue) {
this.textQueue = textQueue;
this.setFont(new Font("OCR A EXTENDED", Font.BOLD, 24));
int arc = 10;
int height = (int) (Game.height * 0.2);
int width = (int) (Game.width - Game.width * 0.1);
int x = Game.width / 2 - width / 2;
int y = (int) (Game.height - height * 1.5);
rr = new RoundRectangle2D.Double(x, y, width, height, arc, arc);
setText(textQueue.remove());
timer.start();
}
private void setText(String text) {
this.text = text;
}
boolean isRunning() {
return timer.isRunning();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
// Set component alpha
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));
// Draw RoundRectangle
g2.setBackground(Color.DARK_GRAY);
g2.fill(rr);
// Draw text
// g2.setColor(Color.BLUE);
final FontMetrics fm = g.getFontMetrics();
Rectangle2D textBounds = fm.getStringBounds(text, g2);
g2.drawString(text, (float) (rr.getCenterX() - (textBounds.getWidth() / 2)), (float) (rr.getCenterY() + textBounds.getHeight() / 2));
}
@Override
public void actionPerformed(ActionEvent e) {
if (alpha >= 0) {
alpha += alphaDelta;
}
if (alpha < 0) {
alpha = 0;
try {
setText(textQueue.remove());
} catch (NoSuchElementException ex) {
timer.stop();
}
alphaDelta *= -1;
} else if (alpha >= 1) {
alpha = 1;
alphaDelta *= -1;
// Sleep 1 sec on full alpha
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
repaint();
}
}
新功能：
public class Game extends JFrame {
...
GameCanvas gameCanvas;
public Game() {
...
gameCanvas = new GameCanvas(); // Spelpanel
getContentPane().add(gameCanvas);
...
pack();
}
}
import javax.swing.*;
import java.awt.*;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;
import java.util.ArrayDeque;
import java.util.NoSuchElementException;
public class GameCanvas extends Canvas implements Runnable {
private final int fps = 24; // FPS
private RoundRectangle2D rr;
private String text;
private float alpha;
private float alphaDelta = 0.05f; // Alpha fade speed
private javax.swing.Timer timer = new Timer(1000 / fps, a -> repaint());
private java.util.Queue<String> textQueue; // Contains lines of texts
public GameCanvas() {
this.setFont(new Font("OCR A EXTENDED", Font.BOLD, 20));
// Intro texts
textQueue = new ArrayDeque<>();
textQueue.add("Welcome to the jungle!");
textQueue.add("We've got fun and games.");
// RoundRectangle
int arc = 10;
int height = (int) (Game.height * 0.2);
int width = (int) (Game.width - Game.width * 0.1);// (int) (Game.width - Game.width * 0.5);
int x = Game.width / 2 - width / 2 - 10;
int y = (int) (Game.height - height * 1.5);
rr = new RoundRectangle2D.Double(x, y, width, height, arc, arc);
this.text = textQueue.remove();
Thread thread = new Thread(this); // Fade thread
thread.start();
timer.start();
}
@Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2 = (Graphics2D) g;
// Set component alpha
// g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));
// Draw RoundRectangle
g2.setBackground(Color.DARK_GRAY);
g2.fill(rr);
// Draw text
final FontMetrics fm = g2.getFontMetrics();
Rectangle2D textBounds = fm.getStringBounds(text, g2);
g2.setColor(Color.WHITE);
g2.drawString(text, (float) (rr.getCenterX() - (textBounds.getWidth() / 2)), (float) (rr.getCenterY() + textBounds.getHeight() / 2));
g2.setColor(Color.DARK_GRAY);
}
@Override
public void run() {
while (true) {
if (alpha >= 0) {
alpha += alphaDelta;
}
if (alpha < 0) {
alpha = 0;
try {
this.text = textQueue.remove();
} catch (NoSuchElementException ex) {
timer.stop();
}
alphaDelta *= -1;
} else if (alpha >= 1) {
alpha = 1;
alphaDelta *= -1;
// Sleep 1 sec on full alpha
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
答案 0 :(得分：0)
这是因为您的gamePanel没有LayoutManager（默认情况下使用FlowLayout）来填充面板中的组件。为了查看内容，将其更改为JPanel gamePanel = new JPanel(new BorderLayout());
但是，在Timer的操作中，您Thread.sleep()。这将冻结整个GUI，因为Timer的动作侦听器在事件调度线程中运行，该线程是Thread，不应sleep。相反，您可以使用第二个Timer或某种o标志变量，也可以使用SwingWorker。