我正在使用泛型,需要在运行时创建泛型类的实例,所以我尝试使用getConstructor()。不幸的是,尽管有正确的签名,我收到NoSuchMethodException,所以我不知道出了什么问题。我将非常感谢您的建议,以便我能够解决这个问题。 :)我已经为CustomerAssembler提供了构造函数。由于使用了泛型,我需要动态创建此类的实例。我已经包含了我正在使用的代码片段。在其中,我调用了getConstructors()来查看构造函数是否存在以及它们的签名。两个构造函数都存在,我使用了正确的签名,所以我不知道为什么我会一直得到这个例外。 Arggg ...希望你会看到我做错了什么。 :)
感谢您的时间和帮助, 麦克
// Here are the constructors for CustomerAssembler.
public CustomerAssembler()
{
super();
}
public CustomerAssembler(
Class<Customer> entityClass,
Class<CustomerPreviewDTO> entityPreviewDTOClass,
Class<CustomerDetailDTO> entityDetailDTOClass,
Class<CustomerUpdateDTO> entityUpdateDTOClass,
EntityManager entityManager)
{
super(entityClass, entityPreviewDTOClass, entityDetailDTOClass, entityUpdateDTOClass, entityManager);
}
以下是例外:NoSuchMethodException:
java.lang.NoSuchMethodException: assemblers.CustomerAssembler.<init>(entities.Customer, dtos.CustomerPreviewDTO, dtos.CustomerDetailDTO, dtos.CustomerUpdateDTO, javax.persistence.EntityManager)
这是代码......
try
{
Class<CustomerAssembler> customerAssemblerClass = CustomerAssembler.class;
Constructor<CustomerAssembler>[] lst = (Constructor<CustomerAssembler>[]) this.customerAssemblerClass.getConstructors();
/* See what the signature is for the non-default constructor, so I can make sure that
getConstructor() is configured properly. Here is what was reported in the debugger:
[0] = {java.lang.reflect.Constructor@10796}"public assemblers.CustomerAssembler()"
[1] = {java.lang.reflect.Constructor@10797}"public assemblers.CustomerAssembler(java.lang.Class,java.lang.Class,java.lang.Class,java.lang.Class,javax.persistence.EntityManager)"
signature = {java.lang.String@10802}"(Ljava/lang/Class<Lentities/Customer;>
Ljava/lang/Class<dtos/CustomerPreviewDTO;>
Ljava/lang/Class<dtos/CustomerDetailDTO;>
Ljava/lang/Class<dtos/CustomerUpdateDTO;>
Ljavax/persistence/EntityManager;)V"
*/
// Configure our constructor call... this.contactAssemblerClass
Constructor<CustomerAssembler> ca =
customerAssemblerClass.getConstructor(
Customer.class,
CustomerPreviewDTO.class,
CustomerDetailDTO.class,
CustomerUpdateDTO.class,
EntityManager.class);
// Create an instance here...
}
catch (NoSuchMethodException e)
{
e.printStackTrace();
}
catch (InstantiationException e)
{
e.printStackTrace();
}
catch (IllegalAccessException e)
{
e.printStackTrace();
}
catch (InvocationTargetException e)
{
e.printStackTrace();
}
catch (Exception e)
{
e.printStackTrace();
}
答案 0 :(得分:1)
customerAssemblerClass.getConstructor(
Customer.class,
CustomerPreviewDTO.class,
CustomerDetailDTO.class,
CustomerUpdateDTO.class,
EntityManager.class);
这将查找具有以下签名的构造函数:
CustomerAssemble(Customer c,
CustomerPreviewDTO cpDTO,
CustomerDetailDTO cdDTO,
CustomerUpdateDTO cuDTO,
EntityManager em)
您的构造函数不会将其作为参数。它需要Class
的4个实例和EntityManager
的实例。
所以代码应该是
customerAssemblerClass.getConstructor(
Class.class,
Class.class,
Class.class,
Class.class,
EntityManager.class);