NullPointerException嘗試播放音頻剪輯

Question

我做了下面給出的類來實現遊戲的「繪圖」並播放其中的聲音。執行時，我得到以下錯誤：

java.lang.NullPointerException 
    at sun.applet.AppletAudioClip.<init>(AppletAudioClip.java:65) 
    at java.applet.Applet.newAudioClip(Applet.java:311) 
    at AllPanels.Sound.<init>(Sound.java:20) 
    at AllPanels.Sound.<clinit>(Sound.java:15) 
    at AllPanels.BailoutGame.mousePressed(BailoutGame.java:124) 
    at java.awt.Component.processMouseEvent(Component.java:6502) 
    at java.awt.Component.processEvent(Component.java:6270) 
    at java.awt.Container.processEvent(Container.java:2229) 
    at java.awt.Window.processEvent(Window.java:2022) 
    at java.awt.Component.dispatchEventImpl(Component.java:4861) 
    at java.awt.Container.dispatchEventImpl(Container.java:2287) 
    at java.awt.Window.dispatchEventImpl(Window.java:2719) 
    at java.awt.Component.dispatchEvent(Component.java:4687) 
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:723) 
    at java.awt.EventQueue.access$200(EventQueue.java:103) 
    at java.awt.EventQueue$3.run(EventQueue.java:682) 
    at java.awt.EventQueue$3.run(EventQueue.java:680) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87) 
    at java.awt.EventQueue$4.run(EventQueue.java:696) 
    at java.awt.EventQueue$4.run(EventQueue.java:694) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) 
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:693) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139) 
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:97) 

請一些人告訴我爲什麼我得到這個錯誤，以及如何解決它！

// Sound類

package AllPanels; 

import java.applet.Applet; 
import java.applet.AudioClip; 

public class Sound { 
    public static final Sound fire = new Sound("/home/vivek/Projects/Java/SniperGame/src/Sounds/50 Cal.wav"); 
    private AudioClip clip; 

    public Sound(String fileName){ 
     try{ 
      clip = Applet.newAudioClip(Sound.class.getResource(fileName)); 
     }catch(Exception e) { 
      System.out.println(e); 
      e.printStackTrace(); 
     } 
    } 

    public void play() { 
     try{ 
      new Thread(){ 
       public void Run(){ 
        clip.play(); 
       } 
      }.start(); 
     }catch(Exception e) { 
      System.out.println(e); 
      e.printStackTrace(); 
     } 
    } 
} 

// Game類 - 繪製遊戲

package AllPanels; 

import java.awt.*; 
import java.awt.event.*; 
public class BailoutGame extends Core implements MouseListener, MouseMotionListener, KeyListener { 

    public static void main(String args[]) { 
     (new Thread(new BailoutGame())).start(); 
    } 

    //Variables 

    @Override 
    public void init(){ 
     super.init(); 
     Window w = s.getFullScreenWindow(); 
     w.addKeyListener(this); 
     w.addMouseListener(this); 
     w.addMouseMotionListener(this); 
    } 

    @Override 
    public synchronized void draw(Graphics2D g) { 
     //some code 
    } 

    @Override 
    public void mouseReleased(MouseEvent e) { } 

    @Override 
    public void mouseClicked(MouseEvent e) { } 

    @Override 
    public void mouseEntered(MouseEvent e) { } 

    @Override 
    public void mouseExited(MouseEvent e) { } 

    @Override 
    public void mouseDragged(MouseEvent e) { } 

    @Override 
    public void keyTyped(KeyEvent e) { } 

    @Override 
    public void keyReleased(KeyEvent e) { } 

    @Override 
    public void mousePressed(MouseEvent e) { 
     if((e.getButton() == MouseEvent.BUTTON1) && bulletsInClip != 0){ 
      Sound.fire.play(); 
      //some Code 
     } 
     if(e.getButton() == MouseEvent.BUTTON3){ 
      reload(); 
     } 
    } 

    @Override 
    public void mouseMoved(MouseEvent e) { 
     //some Code 
    } 

    @Override 
    public void keyPressed(KeyEvent e) { 
    //some Code 
    } 
} 

Answer 1

我強烈懷疑getResource(filename)正在恢復null。

請注意，Class.getResource不需要完整的文件名 - 相對於類或類加載程序根，它需要一個資源名稱。試試這個：

public static final Sound fire = new Sound("/Sounds/50 Cal.wav"); 

假設Sounds目錄嵌入在資源與src作爲資源的根，這應該工作。