java - Term to distinguish "default" vs "made-up" classes in OOP -


arraylists, buffered reader, scanner, etc.. "default" classes "already exist" in language..

unlike, say, public class widthoftable "made up" class , " did not exist in language"..

why there no term distinguish these ideas when teaching? barely discovered difference in college , despite being here 3 years.

actually, there pretty strong distinction between called "default" , "made-up" classes, has package names.

all "default" classes in java.* package (java.lang, java.util, etc.), , no "made up" class use package name starts java..

as fact distinction blurred "when teaching", feeling it's intentional. java language pretty set of keywords , syntax rules plus java.lang.object class nobody avoid extending (and uses few other built-in types string, integer , exceptions).

the jdk java library common use-cases, in cases there better alternatives.

in opinion, mistake teach java.util.calendar or java.util.logging stuff have advantage on jodatime or slf4j because they're in classpath default.


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