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Debug: why does boxed Integer comparison fail for order IDs?

Root cause == on Integer compares references. JVM caches boxed integers only for -128..127.

JavaCore JavaTrickySenior

Orders with ID 128 never match in this filter.

Java

Integer threshold = 127;
Integer orderId = request.getOrderId(); // may be > 127
if (orderId == threshold) {
    applyDiscount();
}

Model answerPreview

== on Integer compares references. JVM caches boxed integers only for -128..127.