问如果不存在创建文件的目录，如何创建目录？

public static  <T> String[] listToArray(List<T> list){

    String [] array = new String[list.size()];

    for (int i =0 ; i<array.length;i++)

        array[i] = list.get(i).toString();

    return array;

}

class Car{

 private String name;

  public Car(String name){

    this.name = name;

  }

 public String toString(){

   return name;

 }

}

final List<Car> carList = new ArrayList<Car>();

carList.add(new Car("BMW"))

carList.add(new Car("Mercedes"))

carList.add(new Car("Skoda"))

final String[] carArray = listToArray(carList);

String[] strings = list.stream().toArray(String[]::new);