Puzzle by Dr Wolfgang Laun: "Which is the smallest non-negative integer value that cannot be stored without loss of precision in a double?"

LowestIntegerWithLossInDouble.java

import java.util.function.LongPredicate;

public class LowestIntegerWithLossInDouble {

	static long findFirst(long lower, long upper, LongPredicate predicate) {
		while (lower < upper) {
			long mid = lower + (upper - lower) / 2;
			if (predicate.test(mid)) {
				upper = mid;
			} else {
				lower = mid + 1;
			}
		}
		return lower;
	}

	static boolean hasLoss(long i) {
		return i != (long) (double) i;
	}

	public static void main(String[] args) {
		System.out.println(findFirst(0, Long.MAX_VALUE, LowestIntegerWithLossInDouble::hasLoss));
	}

}