Check if BigDecimal is an integer in Java

user_127479 0
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What is an efficient way of determining whether a BigDecimal is an integer value in the mathematical sense?

At present I have the following code:

private boolean isIntegerValue(BigDecimal bd) {
    boolean ret;
    
    try {
        bd.toBigIntegerExact();
        ret = true;
    } catch (ArithmeticException ex) {
        ret = false;
    }

    return ret;
}

... but would like to avoid the object creation overhead if possible.

Previously I was using bd.longValueExact() which would avoid creating an object if the BigDecimal was using its compact representation internally, but obviously would fail if the value was too big to fit into a long.

bigdecimal java
7 Answers

Depending on the source/usage of your BigDecimal values it might be faster to check if the scale <= 0 first. If it is, then it's definitely an integer value in the mathematical sense. If it is >0, then it could still be an integer value and the more expensive test would be needed.

user_403420

One possiblity should be to check if scale() is zero or negative. In that case the BigDecimal should have no digits after the decimal point and the number should be a mathematical integer if I understand your question correctly.

Update: If positive, it could still be an integer, but you cannot spare extra object creations for further in-depth checks in that case. An example for such a case is given at the stripTrailingZeros() method javadoc (thanks Joachim for the hint in his answer).

Kosi2801_576010
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