if else within JSP or JSTL

Question

I want to output some HTML code based on some condition in a JSP file   if  condition 1        Some HTML code specific for condition 1   else if  condition 2        Some HTML code specific for condition 2     How can I do that  Should I use JSTL

User · Answer

lt c choose gt   lt c when test    not empty userid and userid ne null   gt         lt sql query dataSource    dbsource   var  usersql  gt                  SELECT   FROM newuser WHERE ID                       lt sql param value    param userid     gt         lt  sql query gt    lt  c when gt    lt c otherwise  gt          lt sql query dataSource    dbsource   var  usersql  gt                   SELECT   FROM newuser WHERE username                        lt sql param value    param username     gt          lt  sql query gt                                   lt  c otherwise gt

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lt    taglib prefix  c  uri  http   java sun com jsp jstl core    gt   lt c set var  val  value  5   gt   lt c choose gt      lt c when test    val     5    gt      Value is 5    lt  c when gt     lt c otherwise gt      Value is not 5    lt  c otherwise gt   lt  c choose gt

User · Answer

If you just want to output different text  a more concise example would be     condition    some text when true     some text when false     It is way shorter than c choose

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Should I use JSTL      Yes   You can use  lt c if gt  and  lt c choose gt  tags to make conditional rendering in jsp using JSTL   To simulate if   you can use    lt c if test  condition  gt  lt  c if gt    To simulate if   else  you can use    lt c choose gt       lt c when test    param enter   1    gt          pizza            lt br   gt       lt  c when gt           lt c otherwise gt          pizzas            lt br   gt       lt  c otherwise gt   lt  c choose gt

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You can write if-else condition inside  lt     gt  in jsp pages and html code outside of  lt     gt   For example        lt           String username    String session getAttribute  username            if username  null           gt                       lt p gt  username is null lt  p gt    html code      lt             else         gt           lt p gt  username is not null lt  p gt    html code      lt                   gt

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In case you want to compare strings  write the following JSTL    lt c choose gt       lt c when test    myvar equals  foo     gt                   lt  c when gt       lt c when test    myvar equals  bar     gt                   lt  c when gt       lt c otherwise gt                   lt  c otherwise gt   lt  c choose gt

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lt    taglib prefix  c  uri  http   java sun com jsp jstl core    gt   lt c set var  isiPad  value  value   gt   lt c choose gt      lt  -- if condition -- gt      lt c when test          gt Html Code lt  c when gt       lt  -- else condition -- gt      lt c otherwise gt Html code lt  c otherwise gt      lt  c choose gt

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The construct for this is    lt c choose gt      lt c when test         gt     lt  c when gt   lt  -- if condition -- gt      lt c when test         gt     lt  c when gt   lt  -- else if condition -- gt      lt c otherwise gt     lt  c otherwise gt      lt  -- else condition -- gt   lt  c choose gt    If the condition isn t expensive  I sometimes prefer to simply use two distinct  lt c if tags - it makes it easier to read

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lt c if test    any cond   var  condition  gt        if part  lt  c if gt   lt c if test     condition   gt        else part  lt  c if gt

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If you want to do the following by using JSTL Tag Libe  please follow the following steps    Requirement  if a number is a grater than equal 40 and lower than 50 then display  Two digit number starting with 4  otherwise  Other numbers     Solutions   1  Please Add the JSTL tag lib on the top of the page         lt    taglib uri  http   java sun com jsp jstl core  prefix  c    gt    2  Please Write the following code    lt c choose gt          lt c when test    params number  gt  40  amp  amp  params number  lt 50   gt                 lt p gt  Two digit number starting with 4   lt  p gt          lt  c when gt          lt c otherwise gt                 lt p gt  Other numbers   lt  p gt          lt  c otherwise gt     lt  c choose gt

User · Answer

simple way      lt c if test    condition   gt        if  lt  c if gt   lt c if test     condition   gt        else  lt  c if gt

User · Answer

In case you want to compare strings  write the following JSTL     lt c choose gt       lt c when test    myvar equals  foo     gt                   lt  c when gt       lt c when test    myvar equals  bar     gt                   lt  c when gt       lt c otherwise gt                   lt  c otherwise gt   lt  c choose gt

[jsp] if...else within JSP or JSTL

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