在此期间,我正在从事一个需要某种抽象的项目,但我不知道如何解决与 java 泛型和类型推断相关的一些问题。
这是源代码的简化架构:
public abstract class BaseDataset
{
// Some data
// Some methods
}
public class DerivedDataset1 extends BaseDataset
{
// Some data
// Implementations of some BaseDataset methods
// Some additional methods
}
public class DerivedDataset2 extends BaseDataset
{
// Some data
// Implementations of some BaseDataset methods
// Some additional methods
}
public interface BaseMeasure<T extends BaseDataset>
{
public float evaluate(T dataset);
}
public class DerivedMeasure1 implements BaseMeasure<DerivedDataset1>
{
@Override
public float evaluate(DerivedDataset1 dataset)
{
// evaluate some measure using DerivedDataset1 methods
return the evaluated measure;
}
}
public class DerivedMeasure2 implements BaseMeasure<DerivedDataset2>
{
@Override
public float evaluate(DerivedDataset1 dataset)
{
// evaluate some measure using DerivedDataset2 methods
return the evaluated measure;
}
}
public class SocialNetworkBuilder
{
public <T extends BaseDataset> void build(T dataset, BaseMeasure<T> measure)
{
float weight = measure.evaluate(dataset);
// ...
}
}
我的问题是,如果在我的主课中,我写了这样的东西:
public class Application
{
public static void main(String [] args)
{
BaseDataset dataset = new DerivedDataset1();
BaseMeasure<? extends BaseDataset> measure = new DerivedMeasure1();
SocialNetworkBuilder socialNetworkBuilder = new SocialNetworkBuilder();
socialNetworkBuilder.build(dataset, measure);
}
}
Eclipse 给了我错误:“SocialNetworkBuilder 类型中的方法 build(T, BaseMeasure) 不适用于参数 (BaseDataset, BaseMeasure)”
我认为问题在于“构建”方法必须确保数据集和度量属于同一类型 T。
如果我做这样的事情:
public class Application
{
public static void main(String [] args)
{
BaseDataset dataset = new DerivedDataset1();
BaseMeasure<? extends BaseDataset> measure = new DerivedMeasure1();
SocialNetworkBuilder socialNetworkBuilder = new SocialNetworkBuilder();
socialNetworkBuilder.build((DerivedDataset1) dataset, (DerivedMeasure1) measure);
}
}
它有效,但我无法以这种方式解决我的问题,因为我在编译时不知道我的“数据集”和“测量”实例的派生类型;应该根据运行时给出的一些参数来实例化“数据集”和“测量”。
我需要在运行时实例化我的“测量”和“数据集”变量,并且仍然能够在它们上调用“构建”方法。
你有一些想法来解决这个问题吗?
谢谢你。