Java Generics 简明教程

Java Generics - Type Erasure

泛型用于在编译时进行更严格的类型检查并提供泛型编程。为了实现泛型行为，Java 编译器应用类型擦除。类型擦除是一个编译器将泛型参数替换为实际类或桥接方法的过程。在类型擦除中，编译器确保不创建额外的类且没有运行时开销。

Generics are used for tighter type checks at compile time and to provide a generic programming. To implement generic behaviour, java compiler apply type erasure. Type erasure is a process in which compiler replaces a generic parameter with actual class or bridge method. In type erasure, compiler ensures that no extra classes are created and there is no runtime overhead.

Type Erasure rules

  1. Replace type parameters in generic type with their bound if bounded type parameters are used.

  2. Replace type parameters in generic type with Object if unbounded type parameters are used.

  3. Insert type casts to preserve type safety.

  4. Generate bridge methods to keep polymorphism in extended generic types.