Can you replicate the Floor function found in Excel in Java?

Question

I have searched the internet but have not found any solutions for my question.

I would like to be able to use the same/replicate the type of FLOOR function found in Excel in Java. In particular I would like to be able to provide a value (double or preferably BigDecimal) and round down to the nearest multiple of a significance I provide.

Examples 1:
Value = 24,519.30235
Significance = 0.01
Returned Value = 24,519.30

Example 2:
Value = 76.81485697
Significance = 1
Returned Value = 76

Example 3:
Value = 12,457,854
Significance = 100
Returned Value = 12,457,800

I am pretty new to java and was wondering if someone knew if an API already includes the function or if they would be kind enough to give me a solution to the above. I am aware of BigDecimal but I might have missed the correct function.

Many thanks

Answer 1

Yes you can.

Lets say given numbers are

76.21445 and

0.01

what you can do is multiply 76.21445 by 100 (or divide per 0.01) round the result to nearest or lower integer (depending which one you want)

and than multiply it by the number again.

Note that it may not exactly print what you want if you will not go for the numbers with decimal precision. (The problem of numbers which in the binary format are not finite in extansion). Also in Math you have the round function taking doing pretty much what you want.

http://docs.oracle.com/javase/7/docs/api/java/lang/Math.html you use it like this

round(200.3456, 2);

one Example Code could be

public static void main(String[] args) {
    BigDecimal value = new BigDecimal("2.0");
    BigDecimal significance = new BigDecimal("0.5");
    for (int i = 1; i <= 10; i++) {
        System.out.println(value + " --> " + floor(value, significance));
        value = value.add(new BigDecimal("0.1"));
    }
}

private static double floor(BigDecimal value, BigDecimal significance) {
    double result = 0;
    if (value != null) {
        result = value.divide(significance).doubleValue();
        result = Math.floor(result) * significance.doubleValue();
    }
    return result;
}