Question

In Java, I want to take a double value and convert it to a BigDecimal and print out its String value to a certain precision.

import java.math.BigDecimal;
public class Main {
    public static void main(String[] args) {
        double d=-.00012;
        System.out.println(d+""); //This prints -1.2E-4

        double c=47.48000;
        BigDecimal b = new BigDecimal(c);
        System.out.println(b.toString()); 
        //This prints 47.47999999999999687361196265555918216705322265625 
    }
}

It prints this huge thing:

47.47999999999999687361196265555918216705322265625

and not

47.48

The reason I’m doing the BigDecimal conversion is sometimes the double value will contain a lot of decimal places (i.e. -.000012) and the when converting the double to a String will produce scientific notation -1.2E-4. I want to store the String value in non-scientific notation.

I want to have BigDecimal always have two units of precision like this: “47.48”. Can BigDecimal restrict precision on conversion to string?

Answer 1

It prints 47.48000 if you use another MathContext:

BigDecimal b = new BigDecimal(d, MathContext.DECIMAL64);

Just pick the context you need.