truncating number after decimal...through built in function in java

i want to truncate a number after decimal through a built in function in java (not javascript). for example开发者_StackOverflow: 69.80000000001 to 69.8

please guide.

What about the Decimal Format class?

I haven't tested this, but: Okay, this should work:

import java.text.DecimalFormat;
import java.math.RoundingMode;
public class Test
{
   public static void main(String args[])
   {
        double i = 69.8999999999;
        DecimalFormat format = new DecimalFormat("#.#"); 
        format.setRoundingMode(RoundingMode.FLOOR);
        String s = format.format(i);
        i = Double.parseDouble(s);
        System.out.println(i); //should be 69.8
   }
}

You can use the scale functionality of BigDecimal:

new BigDecimal(69.80000000001).setScale(1, RoundingMode.HALF_UP).doubleValue();

This is for further using the rounded value. If you just want to print the rounded value but hold the original, DecimalFormat is the right choice as described by Matt.