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

Question

I have the following code in Java;

BigDecimal price; // assigned elsewhere

if (price.compareTo(new BigDecimal(\"0.00\")) == 0) {
    return true;
}
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Answer 1

BigDecimal.ZERO.setScale(2).equals(new BigDecimal("0.00"));

Answer 2

Use compareTo(BigDecimal.ZERO) instead of equals():

if (price.compareTo(BigDecimal.ZERO) == 0) // see below

Comparing with the BigDecimal constant BigDecimal.ZERO avoids having to construct a new BigDecimal(0) every execution.

FYI, BigDecimal also has constants BigDecimal.ONE and BigDecimal.TEN for your convenience.

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Note!

The reason you can't use BigDecimal#equals() is that it takes scale into consideration:

new BigDecimal("0").equals(BigDecimal.ZERO) // true
new BigDecimal("0.00").equals(BigDecimal.ZERO) // false!

so it's unsuitable for a purely numeric comparison. However, BigDecimal.compareTo() doesn't consider scale when comparing:

new BigDecimal("0").compareTo(BigDecimal.ZERO) == 0 // true
new BigDecimal("0.00").compareTo(BigDecimal.ZERO) == 0 // true

Answer 3

Alternatively, signum() can be used:

if (price.signum() == 0) {
    return true;
}

Answer 4

Just want to share here some helpful extensions for kotlin

fun BigDecimal.isZero() = compareTo(BigDecimal.ZERO) == 0
fun BigDecimal.isOne() = compareTo(BigDecimal.ONE) == 0
fun BigDecimal.isTen() = compareTo(BigDecimal.TEN) == 0

Answer 5

There is a constant that you can check against:

someBigDecimal.compareTo(BigDecimal.ZERO) == 0