Java: extends 后有&是什么意思

Question

看待一段代码，一个类的定义，其中&BaseEnum>这里的这个&是什么意思？
publicclassEnumTypeHandler&BaseEnum>extendsBaseTypeHandler

Answer 1

packageTypeVarMembers;classC{publicvoidmCPublic(){}protectedvoidmCProtected(){}voidmCPackage(){}privatevoidmCPrivate(){}}interfaceI{voidmI();}classCTextendsCimplementsI{publicvoidmI(){}}classTest{voidtest(Tt){t.mI();//OKt.mCPublic();//OKt.mCProtected();//OKt.mCPackage();//OKt.mCPrivate();//Compile-timeerror}}ThetypevariableThasthesamemembersastheintersectiontypeC&I,whichinturnhasthesamemembersastheemptyclassCT,definedinthesamescopewithequivalentsupertypes.Themembersofaninterfacearealwayspublic,andthereforealwaysinherited`(unlessoverridden).HencemIisamemberofCTandofT.AmongthemembersofC,allbutmCPrivateareinheritedbyCT,andarethereforemembersofbothCTandT.IfChadbeendeclaredinadifferentpackagethanT,thenthecalltomCPackagewouldgiverisetoacompile-timeerror,asthatmemberwouldnotbeaccessibleatthepointwhereTisdeclared.来自TheJava®LanguageSpecification,JavaSE8Edition$4.4TypeVariablesP58~59

Answer 2

1楼正解&在java中是and的意思，在泛型的应用场景，含义基本不变。publicclassEnumTypeHandler&BaseEnum可以理解为Eextends(Enum&BaseEnum)，结合extends的含义，及E为Enum和BaseEnum的子类