用Java的getResource找不到文件

Question

I am trying to load a file called Test from my class, but somehow Java says, that the file does not exist, while it clearly does and neither the URL object url is null nor does it contain an invalid path and when I debug the program, the File object file has the right path stored in it. When I print out file.getPath() and paste it into the Windows Explorer it opens up just fine. I am running Eclipse, but I tried running the program in a console and it doesn't work either.

public static void main(String[] args) {
    URL url = Test.class.getResource("/Test");
    File file = new File(url.toExternalForm());

    if (!file .exists()) {
      System.out.println("File does not exist: " + file.getPath());
      System.exit(-1);
    }
}

I tried it with getResource("Test") , File("Test") and File("/Test") as well, but that didn't work either. I don't know why this happens know, since I work often with files and never had a problem.

The file I want to load is located in a source folder and yes, I checked, it is recognized as a source folder in Eclipse and is in the classpath. By the way the file is actually just called Test without an extension.

Bin folder:

bin/
  |___package/Test.class
  |___Test

Output (Project is called "Other"):

File does not exist: file:\F:\Development\CoolDirectory\Other\bin\Test

Answer 1

Using Test.class.getResource("/Test"); can cause a lot of trouble as you never know if the resource is a plain file or inside a JAR file are somehow not directly accessible.

Therefore the preferred way is to use getResourceAsStream(String) which returns an InputStream you can directly read from.

The following example used Java 9+ featured:

    byte[] data = null;
    try (InputStream in = Test.class.getResourceAsStream("/Test")) {
        if (in == null) {
            System.out.println("Resource '/Test' does not exist");
            System.exit(-1);
        }
        data = in.readAllBytes();
    }