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javaabstracttype-parameter

Java: Class's type parameter extending its own subclass

could I get an explanation for what this method signature is doing?

AbstractRoad<T extends AbstractRoad.Builder<T>>

where there is a subclass called Builder in AbstractRoad's class.

So AbstractRoad has a type parameter..that extends it's own subclass to allow the class to do what exactly?

Solution

  • It looks like the type parameter is an extension of the Builder... meaning it is expecting any type that is or extends the Builder Subclass

    ArrayList<Inventory<T extends Item>>

    This is an array list of inventories containing items or objects that extend item... i.e.

    Public class Potion extends Item

    would be a valid item in the inventory... T is a generics reference of essentially Object. Please see this link: Generic Types