Java 遍历指定目录下的所有文件

import java.io.*;

class Main {
   public static void main(String[] args) {
      File dir = new File("C:");
      String[] children = dir.list();
      if (children == null) {
         System.out.println( "目录不存在或它不是一个目录");
      }
    else {
         for (int i=0; i< children.length; i++) {
            String filename = children[i];
            System.out.println(filename);
         }
      }
   }
}