Rounding Numbers in Java

Enygma

Hey everyone.
I'm trying to round numbers to two decimal places here, but this method doesn't seem to do anything. Can anyone here spot anything?
Cheers!

private double roundTwoDecimalDouble (double d)
   {
      int DECIMAL_PLACES = 2;
      java.math.BigDecimal bigDec = new java.math.BigDecimal(d);
      bigDec.setScale(DECIMAL_PLACES, java.math.BigDecimal.ROUND_HALF_UP);
      return bigDec.doubleValue();
   }

Enygma

Still don't know why that didn't work but came up with this instead and it works so I guess it's the *right* way to do it

private double round(double d)
{
   int secondInt = 0;
   double finalDouble = 0;
   int tempInt = (int)(d * 1000);
   if ((tempInt % 10) >= 5)
   {
      secondInt = (int)((tempInt/10) + 1); 
   }
   else
   {
      secondInt = (int)(tempInt/10);
   }
   finalDouble = (double)secondInt;
   finalDouble = finalDouble / 100;
   return finalDouble;
}

Ugly but it works

satchmo

You're right, that is ugly!
Try this:

double roundTwoPlaces(double d){
	return Math.round(d * 100) /100.0;
}

DeadBankClerk

public static double round(int places, double number){
c = Math.pow(10, places); // 10^places
return ((int)(number*c))/c;
}

---

- Dead Bank Clerk -
"Build a man a fire, and he'll
be warm for a day. Set a man on
fire, and he'll be warm for the
rest of his life."

satchmo

Doing a cast will always round it down (ie 1.109999 will round to 1.10 instead of 1.11), which isn't very desirable in most cases. You're better of using Math.round().

Enygma

Cheers lads!

psheehan

change your to the following and it will work
BigDecimal newDec=bigDec.setScale(DECIMAL_PLACES, BigDecimal.ROUND_HALF_UP);
return newDec.doubleValue();