Java: Check if two double values match on specific no of decimal places

here is the simple example if you still need this :)

public static boolean areEqualByThreeDecimalPlaces(double a, double b) {

    a = a * 1000;

    b = b * 1000;

    int a1 = (int) a;

    int b1 = (int) b;

    if (a1 == b1) {
        System.out.println("it works");
        return true;
    }

    else
        System.out.println("it doesn't work");
    return false;

If you want a = 1.00001 and b = 0.99999 be identified as equal:

return Math.abs(a - b) < 1e-4;

Otherwise, if you want a = 1.00010 and b = 1.00019 be identified as equal, and both a and b are positive and not huge:

return Math.floor(a * 10000) == Math.floor(b * 10000);
// compare by == is fine here because both sides are integral values.
// double can represent integral values below 2**53 exactly.

Otherwise, use the truncate method as shown in Are there any functions for truncating a double in java?:

BigDecimal aa = new BigDecimal(a);
BigDecimal bb = new BigDecimal(b);
aa = aa.setScale(4, BigDecimal.ROUND_DOWN);
bb = bb.setScale(4, BigDecimal.ROUND_DOWN);
return aa.equals(bb);