3 ms·

Really? Not being a Java guy, what is the explanation for this? Terms like boxing and reference comparison come to mind but I can't stitch them into a narrativ

• Twisol 6y ago
  `Long` is a boxed (reference) type, but small numbers are interned so you get the same reference when boxing a primitive value. Larger numbers aren't interned, so you get fresh boxes. https://stackoverflow.com/questions/1700081/why-is-128-128-false-but-127-127-is-true-when-comparing-integer-wrappers-in-ja https://stackoverflow.com/questions/1700081/why-is-128-128-f...
• croo 6y ago
  Reference comparison it is with a twist: the jvm caches the most common integers. You'll get the same object from -128 to +127 when implicitly assigning value. This is part of the spec, and can be set to a larger pool with -XX:AutoBoxCacheMax (but cannot be turned off). If you explicitly ask for a new object (Long a = new Long(123l);) you will get a new object and the comparison will fail as expected. The moral of the story is to always use .equals().