[英]Java override method with nested classes generic parameters
我正在尝试重写以下方法,但无法弄清楚泛型机制:
public interface MyInterface<T extends MyGenericObject> {
public void read(long id, Callback<T> callback);
public void readAll(Callback<Collection<T>> callback);
}
public class SomeObject extends MyGenericObject {
...
}
public class MyClass implements MyInterface<SomeObject> {
@Override
public void read(long id, **????** callback) {
...
}
@Override
public void readAll(**????** callback) {
...
}
}
请你帮助我好吗?
编辑:我在MyClass和MyInterface之间有一个中间接口,并且通用SomeObject一直没有通过,这就是我的问题...
只需更换每个T
由SomeObject
被传递给MyInterface<T>
// T has become SomeObject = put everywhere SomeObject instead of T
public class MyClass implements MyInterface<SomeObject> {
@Override
public void read(long id, Callback<SomeObject> callback) {
...
}
@Override
public void readAll(Callback<Collection<SomeObject>> callback) {
...
}
}
编辑
您已在注释中提到由于擦除问题而无法编译(注释部分中解释了为什么会出现此错误),但是,对于已发布的代码,这是不可能的:
public interface MyInterface<T extends MyGenericObject> {
void read(long id, Callback<T> callback);
void readAll(Callback<Collection<T>> callback);
}
public interface Callback<T> {}
public class MyGenericObject {}
public class SomeObject extends MyGenericObject {}
public class MyClass implements MyInterface<SomeObject> {
@Override public void read(long id, Callback<SomeObject> callback) {}
@Override public void readAll(Callback<Collection<SomeObject>> callback) {}
}
这段代码编译没有任何错误:
import java.util.Collection;
interface Callback<T> {}
class MyGenericObject {}
interface MyInterface<T extends MyGenericObject> {
public void read(long id, Callback<T> callback);
public void readAll(Callback<Collection<T>> callback);
}
class SomeObject extends MyGenericObject { }
class MyClass implements MyInterface<SomeObject> {
@Override
public void read(long id, Callback<SomeObject> callback) {
}
@Override
public void readAll(Callback<Collection<SomeObject>> callback) {
}
}
如果您收到“ MyClass中的read / readAll与MyInterface中的read / readAll冲突;这两种方法具有相同的擦除,但没有一个覆盖另一个”,则您的代码与您所指示的不同。
可以肯定的是,您只能分别使用Callback<SomeObject> callback
和Callback<Collection<SomeObject>> callback
。
尝试
public class MyClass<T extends SomeObject> implements MyInterface<T> {
现在,您可以在方法实现中使用T。 实例化MyClass时,将指定特定的类。
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