Xamarin Android 绑定到继承泛型类型的 Java 类型 [英] Xamarin Android Binding to Java Type which inherits Generic Type

问题描述

我正在寻找解决以下问题的方法.给定 Java 中的类层次结构:

I'm looking for a workaround for the following problem. Given a class hierarchy in Java:

public interface Bar<T> { 
    getValue<T>();
}

public abstract class BarImpl<T> implements Bar<T> {

}

public class Foo extends BarImpl<Double> {
    @override 
    public Double getValue() {
        // .. 
    }
}

Xamarin.Android 按如下方式生成包装器:

Xamarin.Android generates wrappers as follows:

// Now in C# land
public interface Bar 
{
    // Xamarin.Android omits T Value { get; }
}

public partial abstract class BarImpl : Bar  
{
    // Xamarin.Android omits abstract T Value { get; }
}

public partial class Foo : BarImpl
{
    // COMPILE ERROR HERE. No method to override
    public override java.lang.Double Value 
    {
        get { /* ... */ }
    }
}

现在我很清楚Java编译会去除泛型信息，所以这实际上不是一个容易解决的问题，但我确实想知道:

Now I'm well aware that Java compilation strips out generics information, so this isn't actually an easy problem to solve but I do want to know if:

• 任何人都在 java.android 中遇到过类似的问题

• Anyone has come across similar problems in java.android

您使用了哪些巧妙的解决方案来绑定此类层次结构?

What clever solutions you employed to bind this class hierarchy?

我只对 Foo 上的 Value 的 getter(绑定的 c# 类)以及通过基本接口访问它的某种方式感兴趣(cast 是可以的).

I'm only interested in the getter of Value on Foo (bound c# class) and some way to access it via the base interface (cast is OK).

推荐答案

生成器生成部分类.扩展这些可能是一个解决方案.您所要做的就是将文件添加到 Additions 文件夹并将您的内容添加到部分类.我的想法是这样的:

The generator generates partial classes. Extending these could be a solution. All you have to do, is to add files to the Additions folder and ad your stuff to the partial classes. My idea would look like:

// custom interface
public interface IMyBar<T> : Bar<T>
{
    public T Value { get; }
}

// extend the partial base class
public partial abstract class BarImpl : IMyBar<Java.Lang.Double>  
{
    public abstract Java.Lang.Double Value { get; }
}

// compiler generates the rest
public partial class Foo
{
    // COMPILE ERROR HERE. No method to override
    public override Java.Lang.Double Value 
    {
        get { /* ... */ }
    }
}

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