How do you round a float to 2 decimal places in JRuby?

sprintf('%.2f', number) is a cryptic, but very powerful way of formatting numbers. The result is always a string, but since you're rounding I assume you're doing it for presentation purposes anyway. sprintf can format any number almost any way you like, and lots more.

Full sprintf documentation: http://www.ruby-doc.org/core-2.0.0/Kernel.html#method-i-sprintf

(5.65235534).round(2)
#=> 5.65

Edit

After getting feedback, It seems the original solution didn't work. That's why updated the answer as one of the suggestions.

def float_of_2_decimal(float_n) 
  float_n.to_d.round(2, :truncate).to_f
end

---

Other answers may work, if you want to have rounded numbers of 2 decimal places. But, If you want to have floating point numbers with first two decimal places without rounding, Those answers won't help.

So, to get a floating point number with first two decimal places, I used this technique. Doesn't work in some cases

def float_of_2_decimal(float_n)
  float_n.round(3).to_s[0..3].to_f
end

with 5.666666666666666666666666, it will return 5.66 instead of rounded 5.67. Hope it will help someone

Float#round can take a parameter in Ruby 1.9, not in Ruby 1.8. JRuby defaults to 1.8, but it is capable of running in 1.9 mode.