isawsomethodinjavadeclaredas :
voidfoo(@nullableobjectobj ) )。
{ . }
what ' sthemeaningof @ nullable here？ does it mean the输入could be null？
Without the annotation，the input can still be null，so I guess that's not just it？
itmakesitclearthatthemethodacceptsnullvalues，and that if you override the method，you should also accept null values。
italsoservesasahintforcodeanalyzerslikefindbugs.for example，ifsuchamethoddereferencesitsargumentwithoutcheckingfornulllfirst