?????????????

????1??????a:??heap??????棬???????Bar??instance??????index??bar????Foo??instance??????index???????????????????????

????2??????b:instance??????????????????????Bar??index??????0??bar??????null??Foo??index??????0??

????3??????c:?????65?????????Bar?????????????Bar?????????????????superclass Foo?????????Foo????????????????superclass java.lang.Object?????????

????4??????d:java.lang.Object?????????????Foo????????о??????????Foo static??Foo????????????????Bar???????????????е?41?У????????Bar??????????????????????????1??????????????

????5??????????????Bar????????????е?Foo??????????????????????Σ??????????????Foo????????飬???????г????????????Foo initialization???????Foo?????????壬????e:Foo??index??????100(????????????)?????Foo constructor????Foo????????е?????printIndex??????????printIndex?????????????Bar??д?????????????Bar?е?printIndex??????????e?????????δ??е?Bar??????????壬??????printIndex??????????bar=null??????Bar??index???0?????????????null??0??Foo???????????????

????6???????????????Bar???????Bar??????????飬???Bar initialization??????й??????????Bar constructor?????Bar??index???100??Bar??bar??????????????????null?????null??100??Bar????????ɡ?

????7??Object reference bar???heap??к???????Bar?????????????Bar????????????ж?????????Bar????????ɡ?

????8???????????Bar?????????????Bar????????飬???Bar static??

????9????4-8???????????????????????Foo??????????????Foo initialization???????Foo??????????????Foo constructor????Foo????????е?????printIndex??????????printIndex?????????????Bar??д?????????????Bar?е?printIndex????????????????????Bar???????????????bar???????????????bar?????????????????index????????0?????Bar@4633c1aa??0??Foo???????????????

????10?????Bar????????????????Bar initialization???????Bar??????????Bar constructor??Bar@4633c1aa??100??Bar????????ɡ?

????11??Object reference bar???heap??к???????Bar????????????Bar?????????ɡ?

????12??66?е???bar?????????Bar@4633c1aa??100.

????13??67?д????bar??????????????????????????????????????????????????????Foo initialization??Foo constructor??Bar@4633c1aa??0??Bar initialization??Bar constructor??Bar@4633c1aa??100

?????????????

????//??????65?н????????Bar????
????Foo static
????//??????е?41?н????????Bar????
????Foo initialization
????Foo constructor
????null
????0
????Bar initialization
????Bar constructor
????null
????100
????//??????е?56?е????Bar?????????????????????Bar????
????Bar static
????Foo initialization
????Foo constructor
????Bar@4633c1aa
????0
????Bar initialization
????Bar constructor
????Bar@4633c1aa
????100
????//66?е???????Bar??????????????
????Bar@4633c1aa
????100
????//67?д???????Bar????????????????Bar??????????????
????Foo initialization
????Foo constructor
????Bar@4633c1aa
????0
????Bar initialization
????Bar constructor
????Bar@4633c1aa
????100