Вам также необходимо преобразовать вновь созданные пути к файлам и папкам в строку.
File folder = new File("src\\main\\json\\", idNumber);
folder.mkdir();
if (!folder.exists()) {
try {
folder.createNewFile();
} catch (IOException ex) {
Logger.getLogger(JsonGeneration.class.getName()).log(Level.SEVERE, null, ex);
}
}
...
...
FileOutputStream output = null;
File file;
String content = data.toString();
try {
String folder_location = folder.toString() + "\\";
String filename = "CurrentInfo";
file = new File(folder_location + filename.toString() + ".json");
output = new FileOutputStream(file);
if (!file.exists()) {
file.createNewFile();
}
byte[] content_in_bytes = content.getBytes();
output.write(content_in_bytes);
output.flush();
output.close();
} catch (IOException ex) {
Logger.getLogger(JsonGeneration.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
if (output != null) {
output.close();
}
} catch (IOException e) {
Logger.getLogger(JsonGeneration.class.getName()).log(Level.SEVERE, null, e);
}
}
}