How to write new subfolders in java?

I'm processing some .xml files by using XSLT.

By doing this

public static void main(final String[] args) throws Exception {
        final Transformer transformer = TransformerFactory.newInstance().newTransformer(new StreamSource(
                Paths.get("/myPath/myfile.xsl").toFile()));
        new XsltTransformer(Paths.get("/mypath/source_files"),
                Paths.get("/mypath/target_files"), transformer)
                        .run();
    }

I'm able to transform all the .xml files from source_files folder and save the resulting files in target_files. By adding a subfolder to my source_file like /mypath/source_files/test I'm having this error:

Exception in thread "main" java.lang.IllegalStateException: javax.xml.transform.TransformerException: java.io.FileNotFoundException: /mypath/target_files/test/test.xml (No such file or directory)

So, the source path and the target path must be the same.

How to fix this issue?

There's no class named XsltTransformer in the core libraries, nor are there any popular* ones that match what you've written here.

Perhaps this is your XsltTransformer code? It's not clear from context.

Assuming it is your code, you get a No such file or directory error when you attempt to write to a file that doesn't exist (ordinarily, no problem, that would normally just create the file and write to it)... in a directory that doesn't exist. I think you know that, but the question lacks detail, so I'm highlighting it here.

Whenever you are writing code that creates a file, and you want the behaviour of: "Create whatever directories you need to, first, then write to it", this is how to do that:

public void writeHello(Path p) throws IOException {
    Files.createDirectories(p.getParent());
    Files.write(p, "Hello");
}

The important bit being the createDirectories line. Note that it will silently do nothing (and doesn't throw anything) if p.getParent exists and is already a directory, which is presumably exactly what you want. So, just add that one liner before you write your xslt stuff.

If XsltTransformer is not your own code, there are two options: [1] update your question and explain what library you are using, or [2] do an analysis on your input dir yourself, find all subdirs (recursively, properly), manually make all dirs in the target folder, and then let this XsltTransformer thing at it.

Maybe add the subfolder in XsltTransformer path? Like this:

new XsltTransformer(Paths.get("/mypath/source_files/test"),