[英]Java: Return unknown generic type in method
The method 方法
Filter<T,U> connect(final Filter<T,U> filter) {
...
return filter
}
is in a class 在上课
class Pipe<T>
I get the Error "Cannot resolve U". 我收到错误“无法解析U”。 The idea is to just generically return the same filter with the same two types without knowing the U type.
这个想法是只用相同的两种类型返回相同的过滤器,而无需知道U类型。 How do i do that?
我怎么做?
The goal is to be able to chain without providing type parameters, when they are not necessary because they do not get modified: 目标是能够在不需要提供类型参数的情况下进行链接,而无需提供类型参数,因为它们不会被修改:
(new Pipe<Integer>).connect(new Filter<>(...)).connect(new Pipe<>)...
The second Pipe after the Filter in the above expamle shall implicitly be of the generic type Integer. 上述示例中,紧随过滤器之后的第二个管道应隐式地具有通用类型Integer。
It looks like you are trying to make your method generic . 看来您正在尝试使方法通用 。 To do this simply add generic type
U
to its signature right before return type: 为此,只需在返回类型之前将通用类型
U
添加到其签名中:
<U> Filter<T,U> connect(final Filter<T,U> filter) {
...
return filter
}
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