Code reviewHardcr-g280

Subject CorrectnessLevel Senior–Staff~20 minCommon in Code quality & review interviewsIndustries Software development

Question

Review this Java code that computes how many whole days a subscription has been active and whether a 30-day trial has ended.

Customers span many timezones and the nightly job runs near DST transitions.

What a strong answer looks like

Separate real bugs from style. Rank issues by severity, point at the root cause rather than the symptom, and suggest a concrete fix — specific and kind.

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Code to reviewjava

1long daysActive(Instant start, Instant now) {2    long millis = now.toEpochMilli() - start.toEpochMilli();3    return millis / (24 * 60 * 60 * 1000);4}5 6boolean trialExpired(Subscription sub) {7    long days = daysActive(sub.startedAt(), Instant.now());8    return days >= 30;9}10 11void nightlyJob(List<Subscription> subs) {12    for (Subscription sub : subs) {13        if (trialExpired(sub)) {14            convertToPaid(sub);15        }16    }17}

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