* .wav文件应放在目录中的什么位置？

Question

I am working on sound code for a game. And I was using the following code:

import java.io.*;
import java.net.URL;
import javax.sound.sampled.*;

/**
 * This enum encapsulates all the sound effects of a game, so as to separate the sound playing
 * codes from the game codes.
 * 1. Define all your sound effect names and the associated wave file.
 * 2. To play a specific sound, simply invoke SoundEffect.SOUND_NAME.play().
 * 3. You might optionally invoke the static method SoundEffect.init() to pre-load all the
 *    sound files, so that the play is not paused while loading the file for the first time.
 * 4. You can use the static variable SoundEffect.volume to mute the sound.
 */
public enum SoundEffect {
   EXPLODE("explode.wav"),   // explosion
   GONG("gong.wav"),         // gong
   SHOOT("shoot.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
   }
}

Now when I replace one of the listed *.wav files from the code with my own or even name one of my own to the file name listed from the above code. I receive the follow error:

Exception in thread "main" java.lang.ExceptionInInitializerError
    at soundTest.main(soundTest.java:19)
Caused by: java.lang.NullPointerException
    at com.sun.media.sound.StandardMidiFileReader.getSequence(Unknown Source)
    at javax.sound.midi.MidiSystem.getSequence(Unknown Source)
    at com.sun.media.sound.SoftMidiAudioFileReader.getAudioInputStream(Unknown Source)
    at javax.sound.sampled.AudioSystem.getAudioInputStream(Unknown Source)
    at SoundEffect.<init>(sfx.java:75)
    at SoundEffect.<clinit>(sfx.java:55)

From following the stack URL url is null going in, which is telling me the *.wav file itself is not being read.

I have tried the following lines and yes the *.wav file was present (I am aware that I cannot have three items named the same, I've used one played with it, then commented it out and try again with another one, I just removed the "//" to make is easier to read):

TEST("file://C:/shoot.wav");
TEST("/soundTest/shoot.wav");
TEST("shoot.wav");  

As well as, placing a copy of the file in the directory with the package (default), in the src folder, and of course in the root (c:).

How I am envoking the enum is in my main statement where it is all the standard java, main code but with:

 SoundEffect.SHOOT.play();

Where exactly does the *.wav file need to be at int he directory? Or if there is another issue I am missing please point it out. I am also using the Eclipse IDE "Kepler," on Windows 8.1. I would like to note the posted code is all I have thus far.

Answer 1

There is some discussion in the comments that Eclipse might be the problem. I seriously doubt Eclipse is the problem. I have loaded hundreds of audio files using Eclipse. Usually I put the files in a sub-directory "audio" that is one level below the calling code, and use the relative address form: "audio/mySound.wav".

Here is how I load my URL:

URL url = this.getClass().getResource("audio/" & fileName);

I am puzzled as to why there are MIDI references in your stack trace. MIDI has nothing to do with loading .wav files, and really should not be involved at all. Are you sure this is the correct stack trace? Why are we seeing references to MIDI?

Sometimes an unrecognizable .wav file format will throw unexpected errors. The most common .wav is 16-bit encoding, 44100 bps, stereo, little-endian. Are your .wav files of this format?

There are some aspects of your code that I haven't seen implemented in this manner, particularly the use of ENUMS. I'll take your word all that has been tested and verified. I tend to just name individual sound objects (using a wrapper for wav files with Clip or SourceDataLine for playback) and use them that way. Could be what you have with that is a good organizational tool, but I'm not clear if it is working as intended.

For example, with Static use of SoundEffect, as in SoundEffect.SHOOT.play(), are you sure it is pointing to the shoot.wav? Have you written a test to verify this? Combining ENUMS and static invocations--it's getting a little tricky for me to follow.