java - 在java中获取List 的.class

Question

我有以下功能

编辑:将 int 更改为 Long 类

protected <T> ApiResponse<T> getApiResponse(Object obj, Class<T> clasx) 

如何通过List<Long>类作为第二个参数？

我可以通过List<Long>.class但这不起作用？

Answer 1

Type erasure意味着你只能通过List.class .

来自链接文档:

When a generic type is instantiated, the compiler translates those types by a technique called type erasure — a process where the compiler removes all information related to type parameters and type arguments within a class or method. Type erasure enables Java applications that use generics to maintain binary compatibility with Java libraries and applications that were created before generics.

For instance, Box<String> is translated to type Box, which is called the raw type — a raw type is a generic class or interface name without any type arguments. This means that you can't find out what type of Object a generic class is using at runtime. The following operations are not possible:

public class MyClass<E> {
  public static void myMethod(Object item) {
    // Compiler error
    if (item instanceof E) {
        ...
    }
    E item2 = new E();       // Compiler error
    E[] iArray = new E[10];  // Compiler error
    E obj = (E)new Object(); // Unchecked cast warning
  }
}

The operations shown in bold are meaningless at runtime because the compiler removes all information about the actual type argument (represented by the type parameter E) at compile time.