public void delete(String host) {
    db.delete(TABLE_HOSTS, COLUMN_HOST + " = ?", new String[] { host });
  }
@Test
  public void testDelete() {
    Hosts hosts = new Hosts(RuntimeEnvironment.application, "hosts.db");

    hosts.put("ni.hao", "127.0.0.1");
    assertEquals("ni.hao/127.0.0.1", hosts.get("ni.hao").toString());
    hosts.put("ni.hao", "127.0.0.2");
    hosts.delete("ni.hao");
    assertEquals(null, hosts.get("ni.hao"));

    hosts.delete(null);
  }