Converting Array iteration to lambda expression

Question

I have below code which iterates over Cookies to reset the cookie whose name matches CookieSession.NAME

  Cookie[] cookies = httpServletRequest.getCookies();
        LOGGER.info("Clearing cookies on welcome page");
        if (cookies != null)
            for (Cookie cookie : cookies) {
                if (cookie.getName().equals(CookieSession.NAME)) {                      
                cookie.setValue(null);
                cookie.setMaxAge(0);
                cookie.setPath("/");
                httpServletResponse.addCookie(cookie);
              }
            }

can someone simplify it using java 8 lambda expression

Answer 1

Not sure if it will be simplified, but it can be done, yes:

Arrays.stream(cookies)
      .filter(c -> c.getName().equals(CookieSession.NAME))
      .forEach(cookie -> {
          cookie.setValue(null);
          cookie.setMaxAge(0);
          cookie.setPath("/");
          httpServletResponse.addCookie(cookie);
      });

Answer 2

Arrays.stream(httpsServletRequest.getCookies())
    .filter(cookie -> CookieSession.NAME.equals(cookie.getName()))
    .forEach(cookie -> {
        cookie.setValue(null); 
        cookie.setMaxAge(0); 
        cookie.setPath("/");
        httpServletResponse.addCookie(cookie); 
    });

Answer 3

The for loop could be replaced with a forEach expression:

Arrays.stream(cookies)
      .filter(c -> c.getName().equals(CookieSession.NAME))
      .forEach(c -> {c.setValue(null);
                     c.setMaxAge(0);
                     c.setPath("/");
                     httpServletResponse.addCookie(c);
                    });

Answer 4

Other answers seem to have ignored the if (cookies != null). Also I like peek for several intermediate operations rather than a block. Seems clearer to me.

Optional.ofNullable(httpServletRequest.getCookies())
    .ifPresent(cookies -> Arrays.stream(cookies)
        .filter(cookie -> cookie.getName().equals(CookieSession.NAME))
        .peek(cookie -> cookie.setValue(null))
        .peek(cookie -> cookie.setMaxAge(0))
        .peek(cookie -> cookie.setPath("/"))
        .forEach(httpServletResponse::addCookie));

Answer 5

It is not possible to simplify this using a lambda or forEach.

Also, many people think that you should not use forEach to mutate state in a line like this:

cookies.forEach(cookie -> httpServletResponse.addCookie(cookie));

However, this is really a matter of style. As long as forEach consumes the elements sequentially (rather than in parallel), there is nothing that can actually go wrong as a result of a line like that.

Here is Oracle's advice on the subject.

In my opinion, you should leave your code as it is.