Look for qualified this usages in the same class.

Examples:

    /**
     * @author caikang
     * @date 2017/04/07
     */
    public class UserHolder {
        private static final ThreadLocal userThreadLocal = new ThreadLocal();
        public static void set(User user){
            userThreadLocal.set(user);
        }
        public static User get(){
            return userThreadLocal.get();
        }
        public static void remove(){
            userThreadLocal.remove();
        }
    }
    /**
     * @author caikang
     * @date 2017/04/07
     */
    public class UserInterceptor extends HandlerInterceptorAdapter {
        @Override
        public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
            UserHolder.set(new User());
            return true;
        }
        @Override
        public void afterCompletion(HttpServletRequest request,
            HttpServletResponse response, Object handler, Exception ex) throws Exception {
            UserHolder.remove();
        }
    }