Style Java 8
Path path = Paths.get("logs/error.log");
Files.createDirectories(path.getParent());
Pour écrire sur fichier
Files.write(path, "Log log".getBytes());
Lire 
System.out.println(Files.readAllLines(path));
Exemple complet
public class CreateFolderAndWrite {
    public static void main(String[] args) {
        try {
            Path path = Paths.get("logs/error.log");
            Files.createDirectories(path.getParent());
            Files.write(path, "Log log".getBytes());
            System.out.println(Files.readAllLines(path));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}