Apache Commons Statistics: Interval

Apache Commons Statistics provides statistical intervals.

Example:

import org.apache.commons.statistics.interval.Interval;
import org.apache.commons.statistics.interval.BinomialConfidenceInterval;

int n = 400;
int x = 20;
double alpha = 0.05;
Interval interval = BinomialConfidenceInterval.CLOPPER_PEARSON.fromErrorRate(n, x, alpha);

Browse the Javadoc for more information.