Truncate the fractional part of a BigDecimal when its scale is zero in Java

Question

I need to remove the fractional part of a BigDecimal value when its scale has a value of zero. For example,

BigDecimal value = new BigDecimal("12.00").setScale(2, RoundingMode.HALF_UP);

It would assign 12.00. I want it to assign only 12 to value in such cases.

---

BigDecimal value = new BigDecimal("12.000000").setScale(2, RoundingMode.HALF_UP);

should assign 12,

---

BigDecimal value = new BigDecimal("12.0001").setScale(2, RoundingMode.HALF_UP);

should assign 12.

---

BigDecimal value = new BigDecimal("12.0051").setScale(2, RoundingMode.HALF_UP);

should assign12.01

---

BigDecimal value = new BigDecimal("00.000").setScale(2, RoundingMode.HALF_UP);

should assign 0.

---

BigDecimal value = new BigDecimal("12.3456").setScale(2, RoundingMode.HALF_UP);

should assign 12.35 and alike. Is this possible? What is the best way to do?

Answer 1

For the crosslink from there: https://codereview.stackexchange.com/questions/24299/is-this-the-way-of-truncating-the-fractional-part-of-a-bigdecimal-when-its-scale

Is this possible? What is the best way to do?

Probably stripTrailingZeros().

To check your tests:

public static void main(final String[] args) {
    check(truncate("12.000000"), "12");
    check(truncate("12.0001"), "12");
    check(truncate("12.0051"), "12.01");
    check(truncate("12.99"), "12.99");
    check(truncate("12.999"), "13");
    check(truncate("12.3456"), "12.35");
    System.out.println("if we see this message without exceptions, everything is ok");
}

private static BigDecimal truncate(final String text) {
    BigDecimal bigDecimal = new BigDecimal(text);
    if (bigDecimal.scale() > 2)
        bigDecimal = new BigDecimal(text).setScale(2, RoundingMode.HALF_UP);
    return bigDecimal.stripTrailingZeros();
}

private static void check(final BigDecimal bigDecimal, final String string) {
    if (!bigDecimal.toString().equals(string))
        throw new IllegalStateException("not equal: " + bigDecimal + " and " + string);

}

output:

if we see this message without exceptions, everything is ok

Answer 2

Instead of modifying the original value on my own by hand, I have simply tried to apply some conditions like,

String text="123.008";
BigDecimal bigDecimal=new BigDecimal(text);

if(bigDecimal.scale()>2)
{
    bigDecimal=new BigDecimal(text).setScale(2, RoundingMode.HALF_UP);
}

if(bigDecimal.remainder(BigDecimal.ONE).compareTo(BigDecimal.ZERO)==0)
{
    bigDecimal=new BigDecimal(text).setScale(0, BigDecimal.ROUND_HALF_UP);
}

System.out.println("bigDecimal = "+bigDecimal);

The first if condition checks, if the scale is greater than 2. If so, then perform the rounding operation as specified.

The next if condition checks, if the value of the fractional part yields zero. If so, then truncate it. Two BigDecimal objects that are equal in value but have a different scale (like 2.0 and 2.00) are considered equal by the compareTo() method. Therefore, the condition is satisfied whenever the the value of the fractional part is evaluated to zero.

Otherwise, the original value is left untouched (if the scale is either 1 or 2).

If I'm missing something or it's a wrong thing to implement, then please clarify it.