public static void main(String[] args) {          File f = new File("D:\\test\\fsd");          listChids(f,0);      }      public static void listChids(File f,int level){          String preSrt = "";          for(int i=0;i<level;i++){              preSrt += "----";          }          System.out.println(preSrt+f.getName());          if(!f.isDirectory()){              return ;          }else{              File[] fs = f.listFiles();              for(int i=0;i<fs.length;i++){                  listChids(fs[i], level+1);              }          }      }