Check a collection size with JSTL

Question

How can I check the size of a collection with JSTL   Something like    lt c if test    companies size    gt  0   gt    lt  c if gt

User · Answer

You can use like this     fn length numList

User · Answer

use   fn length companies   gt  0  to check the size  This returns a boolean

User · Answer

As suggested by  Joel and  Mark Chorley in earlier comments     empty companies    This checks for null and empty lists collections arrays  It doesn t get you the length but it satisfies the example in the OP  If you can get away with it this is just cleaner than importing a tag library and its crusty syntax like gt

User · Answer

lt c if test  quot   companies size    gt  0  quot  gt    lt  c if gt   This syntax works only in EL 2 2 or newer  Servlet 3 0   JSP 2 2 or newer   If you re facing a XML parsing error because you re using JSPX or Facelets instead of JSP  then use gt instead of  gt    lt c if test  quot   companies size   gt 0  quot  gt    lt  c if gt   If you re actually facing an EL parsing error  then you re probably using a too old EL version  You ll need JSTL fn length   function then  From the documentation   length  java lang Object  - Returns the number of items in a collection  or the number of characters in a string   Put this at the top of JSP page to allow the fn namespace   lt    taglib prefix  quot fn quot  uri  quot http   java sun com jsp jstl functions quot    gt   Or if you re using JSPX or Facelets   lt     xmlns fn  quot http   java sun com jsp jstl functions quot  gt   And use like this in your page   lt p gt The length of the companies collection is    fn length companies   lt  p gt   So to test with length of a collection   lt c if test  quot   fn length companies  gt 0  quot  gt    lt  c if gt   Alternatively  for this specific case you can also simply use the EL empty operator   lt c if test  quot   not empty companies  quot  gt    lt  c if gt

[jsp] Check a collection size with JSTL

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