doing comparison if else in JasperReports

问题:

I want to do a comparison such as:

if <field> == 0 then "-"

Can somebody tell me the syntax using JasperReports?

回答1:

iReport (JasperReports) uses a Ternary operator. For example, consider the following logic:

IF boolean condition THEN
  execute true code
ELSE
  execute false code
END IF

Using a ternary operator, this becomes:

boolean condition ? execute true code : execute false code

When using a variable with the following expression:

$F{column_value}.intValue() == 42 ? "Life, Universe, Everything" : "Naught"

Then the variable's value would be "Life, Universe, Everything" if, and only if, the integer value of $F{column_value} is equal to 42.

Where things get a little obtuse is when you have to have nested conditions. For these, put the nested conditions in parenthesis and on a separate line:

condition1 ?
  (condition2 ? true_code2 : false_code2) :
  false_code1

So when you need to do many of them:

condition1 ?
  (condition2 ?
    (condition3 ? true_code3 : false_code3) :
    false_code2) :
  (condition4 ? true_code4 : false_code4)

回答2:

example of expression in ireport:

(
    $F{foo} == 0 ?
    "Planned" :
    $F{foo} == 1 ?
    "Reserved" :
    $F{foo} == 2 ?
    "Canceled" :
    $F{foo} == 3 ?
    "Absent" :
    $F{foo} == 4 ?
    "Complete" :
    "Unknown"
)

回答3:

Use if-else condition:

1. if customer name is null write '-' (absent), else write customer name.

Be careful of your field data type!

<textFieldExpression class="java.lang.String">
  <![CDATA[
    $F{CustomerName} == null ? '-' : $F{CustomerName}
  ]]>
</textFieldExpression>