Rounding Decimal Numbers?

[Delta]

How do you round to decimal places?
for example how do I round

8.49999999
to
8.5

Please explain. Thank you.

[Paul]

isn't it Math.round?
like

code:

System.out.println(x + " is approximately " + Math.round(x));

[Tony]

no, Math.round would round to an integer. What you do is you multiply it by 10^number of decimal places, round, and then divide back.

such as
8.499 *10^1
84.99 ~ round
85 /10^1
8.5

[Delta]

That's the thing tony... I asked how to round...

[Tony]

i donno... you can typecast it to an (int)

[wtd]

Do you just need this for formatting text?

[zylum]

tony wrote:

no, Math.round would round to an integer. What you do is you multiply it by 10^number of decimal places, round, and then divide back.

such as
8.499 *10^1
84.99 ~ round
85 /10^1
8.5

i think tony's way is the only way to do it unless there is some weird function i havent heard of...

code:

double num = 8.4999; num *= 10; num = Math.round(num); num /= 10; // or just num = Math.round(num * 10) / 10; System.out.println(num); // gets you 8.5

[Dan]

Thats how i do it also. Alougth u whould think there whould be a method for it some where in one of thous java APIs.

[LiquidDragon]

I always thought there was a round method. But i may be wrong

[zylum]

there is a round method but it rounds to the nearest one not the nearest tenth.

[Delta]

Ok well I found some nice lil rounding methods... (I believe this was just for rounding so I could display the text)

code:

import java.text.*; DecimalFormat decF = new DecimalFormat ("###.##"); System.out.println (decF (99999.999999));

also

code:

decF.setMinimumFractionDigits(2);

would set the format to a minimum of two decimal places

code:

decF.setMaximumFractionDigits(2);

would set the format to a maximum of two decimal places

The decimal format thing is only for text as far as I know (for outting it)...

but when it came to storing the value I usually ended up using 'long' instead of 'int' or 'double'... because long would actually round how I wanted it to... never the less... thanks for the help.... Have a nice day.