Formatting a double and not rounding off

Question

I need to format (and not round off) a double to 2 decimal places.

I tried with:

String s1 = "10.126";
Double f1 = Double.parseDouble(s1);
DecimalFormat df = new DecimalFormat(".00");
System.out.println("f1"+df.format(f1));

Result:

10.13

But I require the output to be 10.12

Solution 1

Call setRoundingMode to set the RoundingMode appropriately:

String s1 = "10.126";
Double f1 = Double.parseDouble(s1);
DecimalFormat df = new DecimalFormat(".00");
df.setRoundingMode(RoundingMode.DOWN); // Note this extra step
System.out.println(df.format(f1));

Output

10.12

Solution 2

You can set the rounding mode of the formatter to DOWN:

df.setRoundingMode(RoundingMode.DOWN);

Solution 3

Why not use BigDecimal

BigDecimal a = new BigDecimal("10.126");
BigDecimal floored = a.setScale(2, BigDecimal.ROUND_DOWN);  //  == 10.12

Comments

[SMA_JAVA]

You mean Math.round(arg0); ?? Actually that would round it off to the closest integer.

[John B]

No DecimalFormat's setRoundingMode

[SMA_JAVA]

Thanks for the suggestion..but i need to use java 1.5 ..i guess the setRoundingMode() is available in 1.6

[SMA_JAVA]

Thanks man....i can use it ...but then i wanted something more compact..and also i need to do a couple of calculations on these values, so any ways there will be some amount of parsing required

[Brad]

See my answer using BigDecimal instead

[Bohemian]

Yes, I am using the current version - 1.6. It would behoove you to upgrade your version too.