//Sample10_01.java

import java.io.File;

class Sample10_01{
    public static void main(String[] args){
        File dir = new File("parent");
        String[] strs = dir.list();
        if(strs!=null){
            for(String str : strs){
                System.out.println(str);
            }
        }else{
            System.out.println("null");
        }

    }
}