Java: Problem comparing String variable with "null" value

Question

I'm getting a String value from an HttpServletRequest with the method getParameter with the prupose to parse it to Integer.

This value can be a "null" String if the value is not setted in the front-end but when I try to compare it the result is always false

Boolean.toString(request.getParameter("parameter") == "null"));
Boolean.toString(request.getParameter("parameter") == null));
Boolean.toString(request.getParameter("parameter").isEmpty()));
Boolean.toString(request.getParameter("parameter").isBlank()));

this outputs

false
false
false
false

Strings should be compared using `equals`. For example: `request.getParameter("parameter").equals("null")` — Michael, Dec 04 '19 at 16:45
Make sure that you check if the string is `"null"` *after* you check if it's `null`, though. — azurefrog, Dec 04 '19 at 16:47
For null safety: `Objects.equals(request.getParameter("parameter"), "null")` :) — Michael, Dec 04 '19 at 16:48

score 0 · Accepted Answer · answered Dec 04 '19 at 16:47

0

Did you try Boolean.toString(request.getParameter("parameter").equals("null"));?

answered Dec 04 '19 at 16:47

SteffenJacobs

402
2
10

Thanks for the reply, this was just what was happening. `==` not compares the value equality. – Gerard Vall Dec 04 '19 at 16:52

Java: Problem comparing String variable with "null" value

1 Answers1