How to check if BigDecimal variable == 0 in java?

java

bigdecimal

precision-matters

java-8

byAlex Kataev·Nov 10, 2024

Evaluating BigDecimal zero equality using the compareTo method is as follows:

if (BigDecimal.ZERO.compareTo(yourBigDecVar) == 0) {
    // zero here, folks!
}

Steer clear of == and equals(). These guys don’t like to play nice - they bring scale into the equation, turning a simple equality check into a potential minefield of false negatives. Stick with compareTo for precision, it's your dependable ally.

Side roads and scenic routes: exploring alternatives

Since necessity is the mother of invention, we naturally have several ways to skin this cat.

Turning to `signum()` for a quick check

For speed demons out there, signum() offers a NASCAR-worthy pit-stop:

if (myBigDec.signum() == 0) {
    // zero, zilch, nada - name it as you will
}

signum() throws -1, 0, or 1 at you depending on whether your number's negative, nil, or positive. Pretty handy, quick, and scale-skirtin'.

`equals()` vs `compareTo()` : Thriller Night

equals() and compareTo() are as different as Michael Jackson and his "Thriller" alter ego:

equals(): Demands the same value and scale, or it ain’t budging.
compareTo(): Doesn’t bat an eye at scale; it's all about the number.

To underline, behold this paradox:

new BigDecimal("0.00").equals(BigDecimal.ZERO) // Mike Tyson's unexpected knockout, returns false

While:

new BigDecimal("0.00").compareTo(BigDecimal.ZERO) == 0 // Usain Bolt stays on track, returns true

Appreciating these quirks is pivotal to avoid tripping over false negatives.

Snippets for speedsters

signum() often leaves compareTo() in the dust when zero checking is the name of the game. Plus, a regular date with constants like BigDecimal.ZERO can save you from creating superfluous objects - a win for efficiency.

Precision matters: dating the scale

Dabbling in financials and precision data? Then dating the scale is something you can't bow out of.

Messing with money

Juggling monetary values? Precision is your dance partner. Let's say you're comparing Rami Malek to a sworn Freddie Mercury impersonator - there's going to be a difference, subtle as it is:

BigDecimal valueWithScale = bigDecVar.setScale(2, RoundingMode.HALF_UP);
if (BigDecimal.ZERO.compareTo(valueWithScale) == 0) {
    // Disguise unmasked! Our value is a Freddie impersonator.
}