public static synchronized Class<?> getClass(String name, Configuration conf
                                            ) throws IOException {
    Class<?> writableClass = NAME_TO_CLASS.get(name);
    if (writableClass != null)
      return writableClass;
    try {
      return conf.getClassByName(name);
    } catch (ClassNotFoundException e) {
      IOException newE = new IOException("WritableName can't load class: " + name);
      newE.initCause(e);
      throw newE;
    }
  }
@Test
  public void testGoodName() throws Exception {
    Configuration conf = new Configuration();
    Class<?> test = WritableName.getClass("long",conf);
    assertTrue(test != null);
  }