How can I use Hamcrest to check if each element in an array of doubles is “close” to each element in another array?

Question

I would like to compare two arrays of doubles. Using vanilla JUnit, I can do:

double[] a = new double[]{1.0, 2.0, 3.0};
double[] b = new double[]{1.0, 2.0, 3         


        

Answer 1

If you change a to a Double[] then you can do assertThat(a, arrayCloseTo(b, .2)); with this helper method:

public static Matcher<Double[]> arrayCloseTo(double[] array, double error) {
    List<Matcher<? super Double>> matchers = new ArrayList<Matcher<? super Double>>();
    for (double d : array)
        matchers.add(closeTo(d, error));
    return arrayContaining(matchers);
}

You can do it with a primitive array as well, but you will need a custom matcher for that.