How to create a file Path from a folder Path

I am probably overlooking something but what's the right way to create a file Path from a folder Path? This is what I'm doing but it seems wrong to convert the folder path to a string just to reconstruct it. Is there a better way?

Path testFolder = Files.createTempDirectory("fileFinder");
Path testFile = Paths.get(testFolder.toString(), "sample.java");
Files.createFile(testFile);