Java不会读取具有相对路径的图片和音频文件

Question

In java i programmed a small program to play audio file and sow pictures:
At first i make a final String with the path and then i made a file object.
At least i save the returned array in my "tracks" variable. This is my code:

private static final String PATH = "../src/audio/";
private static final File FILE = new File(PATH);
tracks = liesAudioDateien(file);

private AudioClip[] liesAudioDateien (File inputFile) {
    File[] dateFileArray;
    AudioClip[] tracks;
    dateFileArray = inputFile.listFiles();
    tracks = new AudioClip[dateFileArray.length];
    for (int i = 0; i < tracks.length; i++) {
        if (dateFileArray[i].isFile()) {
            try {
                tracks[i] = Applet.newAudioClip(dateFileArray[i].toURL());
            } catch (IOException ex) {
                System.err.println("Oops!: -- " + ex.toString());
            }
        }

    }
    return tracks;   

If I run this code, I get an error:

Exception in thread "main" java.lang.NullPointerException
    at source.Sound.liesAudioDateien(Sound.java:32)

Sound.java:32:
This is tracks = new AudioClip[dateFileArray.length]; line.

If i try with an absolute path, it does work! What i do wrong?

Answer 1

Your path is relative, which is resolved to be relative to the current working directory. The current working directory is not what you think it is.

Try to do this before inputFile.listFiles() ;

System.out.println(inputFile.getAbsolutePath());

And see what Java thinks the absolute path should be.

Answer 2

将"../src/audio/"更改为"./src/audio/"

Answer 3

File.listFiles returns null if the abstract pathname does not denote a directory.

You need to make sure inputFile does denote a directory to ensure dateFileArray is not null .

Answer 4

Try it with File.separator in place of forward/backward slash. ex:

String soundDir = "." + File.separator + "folderName" + File.separator;
String fileName = "sound.wav";
String filePath = soundDir+ + fileName;