我正试图在我的游戏中播放声音，例如当我按下我的UP键时，听到激光的声音，但我收到错误，我不明白为什么。我很可能在我的方法中调用了错误的代码，或者我的错误来源了。
Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: Could not initialize class SpaceInvadersPanel$SoundEffect
at SpaceInvadersPanel$4.keyPressed(SpaceInvadersPanel.java:69)
at java.awt.Component.processKeyEvent(Unknown Source)
at javax.swing.JComponent.processKeyEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
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import java.awt.event.*;
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Color;
import javax.sound.sampled.*;
import java.io.*;
import java.net.URL;
import java.applet.*;
import java.awt.*;
import java.io.File;
import java.net.MalformedURLException;
public class SpaceInvadersPanel extends JPanel {
private static final long serialVersionUID = 1L;
private Timer timer;
private Player1 player1;
private Player1weapon player1weapon;
private Player2 player2;
private Player2weapon player2weapon;
public Image background;
public ImageIcon bg;
int width, height;
public SpaceInvadersPanel() {
bg = new ImageIcon("src/resources/BG.png");
background = bg.getImage();
ActionListener action = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
if (player1 != null && player2 != null) {
player1.updateForNewFrame();
player1weapon.updateForNewFrame();
player2.updateForNewFrame();
player2weapon.updateForNewFrame();
}
repaint();
}
};//end Actionlistener()
timer = new Timer( 10, action );
addMouseListener( new MouseAdapter() {
public void mousePressed(MouseEvent evt) {
requestFocus();
}
} );
addFocusListener( new FocusListener() {
public void focusGained(FocusEvent evt) {
timer.start();
repaint();
}
public void focusLost(FocusEvent evt) {
timer.stop();
repaint();
}
} );
addKeyListener( new KeyAdapter() {
public void keyPressed(KeyEvent evt) {
int code = evt.getKeyCode();
if (code == KeyEvent.VK_LEFT) {
player1.centerX -= 10;
}
if (code == KeyEvent.VK_RIGHT) {
player1.centerX += 10;
}
if (code == KeyEvent.VK_UP) {
if (!player1weapon.isFalling)
player1weapon.isFalling = true;
SoundEffect.SHOOT.play();
}
if (code == KeyEvent.VK_A) {
player2.centerX -= 10;
}
if (code == KeyEvent.VK_D) {
player2.centerX += 10;
}
if (code == KeyEvent.VK_S) {
if (!player2weapon.isFalling)
player2weapon.isFalling = true;
SoundEffect.SHOOT.play();
}
}//end KeyPressed()
} );//end KeyAdapter()
}//end SpaceInvadersPanel
public void paintComponent(Graphics g) {
g.drawImage(background,0,0,700,700,null);
if (player1 == null && player2 == null) {
width = 700;
height = 700;
player1 = new Player1();
player2 = new Player2();
player1weapon = new Player1weapon();
player2weapon = new Player2weapon();
}
if (hasFocus())
g.setColor(Color.BLACK);
else {
g.setColor(Color.GREEN);
g.drawString("CLICK TO START THE GAME", 270, 350);
g.drawString("Player1", 550, 500);
g.drawString("Right arrow - Move Right", 550, 515);
g.drawString("Left arrow - Move Left", 550, 530);
g.drawString("Up arrow - Fire", 550, 545);
g.drawString("Player2", 50, 150);
g.drawString("D key - Move Right", 50, 165);
g.drawString("A key - Move Left", 50, 180);
g.drawString("S key - Fire", 50, 195);
}
player1weapon.draw(g);
player2weapon.draw(g);
player1.draw(g);
player2.draw(g);
} // end paintComponent()
public enum SoundEffect {
SHOOT("sounds/Laser.wav"); // bullet
// Nested class for specifying volume
public static enum Volume {
MUTE, LOW, MEDIUM, HIGH
}
public static Volume volume = Volume.LOW;
// Each sound effect has its own clip, loaded with its own sound file.
private Clip clip;
// Constructor to construct each element of the enum with its own sound file.
SoundEffect(String soundFileName) {
try {
// Use URL (instead of File) to read from disk and JAR.
URL url = this.getClass().getClassLoader().getResource(soundFileName);
// Set up an audio input stream piped from the sound file.
AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(url);
// Get a clip resource.
clip = AudioSystem.getClip();
// Open audio clip and load samples from the audio input stream.
clip.open(audioInputStream);
} catch (UnsupportedAudioFileException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (LineUnavailableException e) {
e.printStackTrace();
}
}
// Play or Re-play the sound effect from the beginning, by rewinding.
public void play() {
if (volume != Volume.MUTE) {
if (clip.isRunning())
clip.stop(); // Stop the player if it is still running
clip.setFramePosition(0); // rewind to the beginning
clip.start(); // Start playing
}
}
// Optional static method to pre-load all the sound files.
static void init() {
values(); // calls the constructor for all the elements
}
}
public class Player1{
int centerX, centerY;
int width, height;
int explosionFrameNumber;
int score = 0;
boolean isExploding;
public Image p1;
public ImageIcon p1stock;
public Image explodep1;
public ImageIcon explodep1icon;
Player1() {
centerX = 500;
centerY = 600;
isExploding = false;
}
void updateForNewFrame() {
if (isExploding) {
explosionFrameNumber++;
if (explosionFrameNumber == 15) {
width = 700;
centerX = (int)(width*Math.random());
centerY = 600;
isExploding = false;
}
}
if(centerX <= -30)
centerX = -10;
else if(centerX > 640)
centerX = 630;
}//end updateForNewFrame
void draw(Graphics g) {
p1stock = new ImageIcon("src/resources/player1.png");
p1 = p1stock.getImage();
explodep1icon = new ImageIcon("src/resources/explosion.png");
explodep1 = explodep1icon.getImage();
g.setColor(Color.RED);
g.drawString("Score: " + score, 20, 450);
g.drawImage(p1, centerX, centerY, p1.getWidth(null), p1.getHeight(null),null);
if (isExploding) {
g.drawImage(explodep1, centerX - 4*explosionFrameNumber + 40, centerY - 2*explosionFrameNumber + 10,
8*explosionFrameNumber, 4*explosionFrameNumber,null);
}
}//end draw()
}//end Player1
public class Player2{
int centerX, centerY;
int width, height;
boolean isExploding;
int explosionFrameNumber;
int score = 0;
public Image p2;
public Image explodep2;
public ImageIcon p2stock;
public ImageIcon explodep2icon;
Player2() {
centerX = 50;
centerY = 30;
isExploding = false;
}
void updateForNewFrame() {
if (isExploding) {
explosionFrameNumber++;
if (explosionFrameNumber == 15) {
isExploding = false;
width = 700;
centerX = (int)(width*Math.random());
centerY = 30;
}
}
if(centerX <= -30)
centerX = -10;
else if(centerX > 640)
centerX = 630;
}//end updateForNewFrame()
void draw(Graphics g) {
p2stock = new ImageIcon("src/resources/player2.png");
p2 = p2stock.getImage();
explodep2icon = new ImageIcon("src/resources/explosion.png");
explodep2 = explodep2icon.getImage();
g.setColor(Color.RED);
g.drawString("Score: " + (score), 20, 250);
g.drawImage(p2, centerX, centerY, p2.getWidth(null), p2.getHeight(null),null);
if (isExploding) {
g.drawImage(explodep2, centerX - 4*explosionFrameNumber + 40, centerY - 2*explosionFrameNumber + 10,
8*explosionFrameNumber, 4*explosionFrameNumber,null);
}
}//end draw()
} //end Player2
public class Player1weapon{
int centerX, centerY;
boolean isFalling;
public Image laserp1;
public ImageIcon lp1icon;
public Player1weapon() {
isFalling = false;
}
void updateForNewFrame() {
if (isFalling) {
if (centerY < player2.centerY - 50) {
isFalling = false;
}
else
if (Math.abs(centerX - player2.centerX - 40) <= 30 && Math.abs(centerY - player2.centerY + 35) <= 70) {
player2.isExploding = true;
player2.explosionFrameNumber = 1;
isFalling = false;
player1.score+=10;
}
else
centerY -= 20;
}//end if
}//end updateForNewFrame()
void draw(Graphics g) {
lp1icon = new ImageIcon("src/resources/laserplayer1.png");
laserp1 = lp1icon.getImage();
if (!isFalling) {
centerX = player1.centerX + 37;
centerY = player1.centerY + 23;
}
g.drawImage(laserp1, centerX, centerY - 8, laserp1.getWidth(null), laserp1.getHeight(null),null);
}//end Draw()
}//end player1weapon
public class Player2weapon{
int centerX, centerY;
boolean isFalling;
public Image laserp2;
public ImageIcon lp2icon;
public Player2weapon() {
isFalling = false;
}
void updateForNewFrame() {
if (isFalling) {
if (centerY > player1.centerY + 50) {
isFalling = false;
}
else
if (Math.abs(centerX - player1.centerX) <= 20 && Math.abs(centerY - player1.centerY + 20) <= 20) {
player1.isExploding = true;
player1.explosionFrameNumber = 1;
isFalling = false;
player2.score+=10;
}
else
centerY += 20;
}//end if
}//end updateForNewFrame()
void draw(Graphics g) {
lp2icon = new ImageIcon("src/resources/laserplayer2.png");
laserp2 = lp2icon.getImage();
if (!isFalling) {
centerX = player2.centerX + 1;
centerY = player2.centerY + 15;
}
if (isFalling) {
g.drawImage(laserp2, centerX + 36, centerY - 8, laserp2.getWidth(null), laserp2.getHeight(null),null);
}
}//end Draw()
}//end player2weapon
/*public class Asteroid{
int centerX, centerY;
boolean isFalling;
public Image asteroid;
public ImageIcon icon;
public Asteroid() {
isFalling = false;
icon = new ImageIcon("src/resources/laserplayer2.png");
asteroid = icon.getImage();
}
void updateForNewFrame() {
if (isFalling) {
if (centerY > player1.centerY + 50) {
isFalling = false;
}
else
if (Math.abs(centerX - player1.centerX) <= 20 && Math.abs(centerY - player1.centerY + 20) <= 20) {
player1.isExploding = true;
player1.explosionFrameNumber = 1;
isFalling = false;
player2.score+=10;
}
else
centerY += 50;
}//end if
}//end updateForNewFrame()
void draw(Graphics g) {
if (!isFalling) {
centerX = player2.centerX + 1;
centerY = player2.centerY + 15;
g.drawImage(asteroid, centerX + 36, centerY - 8, asteroid.getWidth(null), asteroid.getHeight(null),null);
}
if (isFalling) {
g.drawImage(asteroid, centerX + 36, centerY - 8, asteroid.getWidth(null), asteroid.getHeight(null),null);
}
}//end Draw()
}//end asteroid*/
}//end SpaceInvadersPanel
答案 0 :(得分：1)
stacktrace指出当程序在运行时尝试访问它时，类未被初始化。在这种情况下，堆栈跟踪中也应该有ExceptionInInitializerError。如果是，您可以在SoundEffect构造函数中放置一个Exception或Throwable块来查看确切的错误：
catch (Exception e) {
e.printStackTrace();
}
如有疑问，可以查看 - Debugging a NoClassDefFoundError