Get your own Java server
import java.io.File;

public class Main {
  public static void main(String[] args) {
    File myFolders = new File("parentFolder/childFolder");
    myFolders.mkdirs();
    File parent = new File("parentFolder");
    System.out.println(parent.isDirectory());
    System.out.println(myFolders.isDirectory());
  }
}

              
true
true