A question about formatNumber and decimal places

[Thomas Kennedy]

I'm printing currency values to the screen using <fmt:formatNumber>. If my numeric value has a non-zero fractional part I want exactly two decimal places. If the fractional part is zero I want the decimal places omitted.

so 45.75 prints as $45.75
but 201.00 prints as $201

How can I do that?

[Paul Clapham]

So that means that 18.30 should print as $18.30 and not as $18.3? In that case I think you're going to need two different formatters and some kind if-then-else to distinguish the two cases. Writing a custom tag might be the right way to go here.

[Bear Bibeault]

Why two formatters? What are the two cases? I only see one.

No custom tag is necessary, the <fmt:formatNumber> tag should do just fine.

But the OP hasn't shown that any effort has been put into the problem yet. What formats have been tried that aren't working?

[Paul Clapham]

Thomas Kennedy wrote:If my numeric value has a non-zero fractional part I want exactly two decimal places.

If the fractional part is zero I want the decimal places omitted.

These are the two cases I saw. I don't see how to implement that with a single DecimalFormat.

[Bear Bibeault]

Ah. I thought that no-trailing was an undesirable outcome.

In that case, I'd simply use the ternary operator to choose between the two patterns.

<fmt:formatNumber pattern="${decision ? 'pattern1':'pattern2'}" ...   />

[Thomas Kennedy]

Is there anything in the fn library that can perform decision in a robust way? All I can think of is to check if the String representation of the value ends with ".00", and that sounds ugly. BTW does Oracle have a documentation page for EL? Thank you.

[Paul Clapham]

Expression Language Specification Version 2.1

[Paul Clapham]

And no, there isn't an EL function in the fn: namespace which does that. But you don't need one, either. One of the EL operators is sufficient.

[Bear Bibeault]

What type is the numeric value? How would you test it in a Java expression to see if it were a whole number or not?

[Thomas Kennedy]

In Java I would use Math.round() to compare the value to itself. So I could step out to a scriptlet but would prefer to avoid that.

[Bear Bibeault]

OK, so let's say you've been forbidden to use the Math class. How would you do with basic operators?