BigDecimal - strange errors

[Don Smathers]

Please look a the following code and its result
import java.math.*;
public class TestEm
{
public static void main ( String [ ] args )
{
System.out.println( new BigDecimal(0.1234567891234567890001).setScale( 20, BigDecimal.ROUND_DOWN ) ) ;
System.exit(0);
}
}
// running the app produces 0.12345678912345678379, the 379 was 90001.
Any ideas on a> why this is happening and
b> how to get BigDecimal to work properly??
Thanks - Don

[Carl Trusiak]

The problem is occuring because of double and not BigDecimal. You are using the constructor that takes a double agruement and double is rounding the value before it gets to your Object. Using the constructor that uses a String will correct your problem.

import java.math.*;
public class TestEm
{
    public static void main ( String [ ] args )
    {
        System.out.println( new BigDecimal("0.1234567891234567890001").setScale( 20, BigDecimal.ROUND_DOWN ) ) ;
    }
}

------------------
Hope This Helps
Carl Trusiak, SCJP2
[This message has been edited by Carl Trusiak (edited March 23, 2001).]

[Don Smathers]

Carl - thanks Even on re-reading the 'Dictionary' on class libraries, it took two more readings to catch the subtlety that a REALLY big decimal requires a string input.
In fact, it looks like a string may always be the best way to instantiate a BigDecimal object. Does this make good programming sense / practice ?