java反射：避免警告unchecked调用getConstructor（Class ...）作为原始类型的成员Class(java reflection :Avoid warning unchec

java反射：避免警告unchecked调用getConstructor（Class <？> ...）作为原始类型的成员Class(java reflection :Avoid warning unchecked call to getConstructor(Class<?>…) as a member of the raw type Class)

我看过这篇文章

java：unchecked调用getConstructor（java.lang.Class <？> ...）

for (Map.Entry<String, Class> entry : connectionRepository.entrySet()) { if (/*someconditionhere*/) { try { cwsConnection = (CWSConnection)entry.getValue().getConstructor().newInstance(); break; } catch (InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException e) { logger.error("Could not Create instance of CWSConnection for site version:\"{}\" Error:\"{}\"", entry.getKey(), e.getMessage(), e); } } }

编译这段代码时，我收到警告

警告：[unchecked] unchecked调用getConstructor（Class ...）作为原始类型Class的成员

我只想得到CWSConnection的默认构造函数，因此，我不应该将任何参数传递给getConstructor（Class ...）方法。 有没有更好的方法来获得默认的构造函数（没有参数的那个）

（我知道@SupressWarning注释会抑制此警告。）

I have read this post

java: unchecked call to getConstructor(java.lang.Class<?>...)

for (Map.Entry<String, Class> entry : connectionRepository.entrySet()) { if (/*someconditionhere*/) { try { cwsConnection = (CWSConnection)entry.getValue().getConstructor().newInstance(); break; } catch (InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException e) { logger.error("Could not Create instance of CWSConnection for site version:\"{}\" Error:\"{}\"", entry.getKey(), e.getMessage(), e); } } }

While compiling this piece of code I am getting a warning

warning: [unchecked] unchecked call to getConstructor(Class...) as a member of the raw type Class

I just wanted to get the default constructor of CWSConnection, therefore, I should not pass any parameters to getConstructor(Class...) method. Is there any better approach to get the default constructor(The one without arguments)

(I know @SupressWarning annotation will suppress this warning.)

最满意答案

只需将您的循环声明更改为

for (Map.Entry<String, Class<?>> entry : connectionRepository.entrySet()) {

你有这个错误，因为你使用参数化的Class作为原始类型。 在这里你可以阅读有关泛型和通配符 。 您可以使用Class<?>并避免此错误。 但是转换为CWSConnection仍然是必需的。 您可以通过拥有Map<String, Class<CWSConnection>>而不是Map<String, Class<?>>来避免它。

Just change your loop declaration to

for (Map.Entry<String, Class<?>> entry : connectionRepository.entrySet()) {

You've got this error because you use parametrised Class as a raw type. Here you can read about generics and wildcards. You can use Class<?> and avoid this error. But cast to CWSConnection is still required. You can avoid it by owning a Map<String, Class<CWSConnection>> instead of Map<String, Class<?>>.