Java泛型擦除类型转换

Question

当类型信息由于擦除而在运行时不可用时，java编译器如何知道为通用集合中的对象提供适当的转换？

Answer 1

Whenever you call eg list.get(foo) , and the list is an ArrayList<String> , then the result of get is casted to a String by the caller , not the callee. The caller knows at compile time what the result should be cast to (a String ), so the cast can be inserted there.

Answer 2

As per oracle tutorial

• Replace all type parameters in generic types with their bounds or Object if the type parameters are unbounded. The produced bytecode, therefore, contains only ordinary classes, interfaces, and methods.
• Insert type casts if necessary to preserve type safety.
• Generate bridge methods to preserve polymorphism in extended generic types.

So, your class file contains either bounded class (or) Object instead of generic type.