private static File insertFile(Drive service, String title, String description,
  String parentId, String mimeType, String filename) {
// File's metadata.
File body = new File();
body.setTitle(title);
body.setDescription(description);
body.setMimeType(mimeType);

// Set the parent folder.
if (parentId != null && parentId.length() > 0) {
  body.setParents(
      Arrays.asList(new ParentReference().setId(parentId)));
}

// File's content.
java.io.File fileContent = new java.io.File(filename);
FileContent mediaContent = new FileContent(mimeType, fileContent);
try {
  File file = service.files().insert(body, mediaContent).execute();

  // Uncomment the following line to print the File ID.
  // System.out.println("File ID: " + file.getId());

  return file;
} catch (IOException e) {
  System.out.println("An error occured: " + e);
  return null;
}
}