How to Reliably Compare Double Values in Java and Avoid Precision Errors?

Double Value Comparison in Java: Addressing Precision Errors

Comparing double values in Java can be a tricky task due to potential precision errors. A straightforward comparison, like the one shown below, may lead to unexpected results:

double a = 1.000001;
double b = 0.000001;

boolean result = (a - b == 1.0); // False

This code prints false because the subtraction operation results in 0.9999999999999999, which is not strictly equal to 1.0. To overcome this issue, we need a more precise comparison method.

One approach is to calculate the absolute difference between the two values and compare it to a small tolerance value. For example:

double c = Math.abs(a - b - 1.0);
boolean result = (c <= 0.000001); // True

This code introduces a tolerance of 0.000001, so as long as the absolute difference between c and 1.0 is within this range, the comparison will evaluate to true. The Math.abs() method ensures that the absolute value is considered, disregarding any sign differences.

By using this technique, we can account for the potential precision errors and perform reliable comparisons of double values. This approach is particularly useful when working with floating-point data, where exact equality comparisons are not always practical.

The above is the detailed content of How to Reliably Compare Double Values in Java and Avoid Precision Errors?. For more information, please follow other related articles on the PHP Chinese website!