Wait... Why is 4 and 5 in a cache? Does Java keeps EVERY integer value in a cache?,(reply>), @Anurag Baundwal do you know why that is? Wouldn't it be easier and faster to simply add numbers in the processing unit instead of keeping a cache of signed 8-bit value?,(reply>), It explains it in the video, only signed 8 bits ints are stored in cache. There must be something like common cases where that is useful, because this is only for wrapped integers in the Integer class, so it's really acache of objects, not integers