运行可执行文件 jar

Question

I have a maven project in Eclipse. Under the src/main/resources I have a directory named "directoryToCopy" containing files. Once I run my project, I want to copy "directoryToCopy" under a local directory "localDirec" in my desktop.

I used this:

File localDirec = new File("c:/desktop/scripts");
URI urlDir = ClassLoader.getSystemResource("directoryToCopy").toURI();
File srcDir = new File(urlDir.getPath());
FileUtils.copyDirectory(srcDir, localDirec);

This works fine locally, but when I want to run it as an executable jar file I get NullPointerException

Exception in thread "main" java.lang.NullPointerException
        at java.base/java.io.File.<init>(File.java:278)

Any suggestion please?

Answer 1

You can always, try printing the path

System.out.println(getClass().getResource(getClass().getSimpleName() + ".class"));

Class's getResource() - documentation states the difference:

"This method delegates the call to its class loader, after making these changes to the resource name: if the resource name starts with "/", it is unchanged ; otherwise, the package name is prepended to the resource name after converting "." to "/". If this object was loaded by the bootstrap loader, the call is delegated to ClassLoader.getSystemResource."

Use / when path should not be changed, try printing the loaded path, it would make things clear.