匕首2-两个提供相同界面的方法 [英] Dagger 2 - two provides method that provide same interface

问题描述

让我说：

public interface Shape  {}


public class Rectangle implements Shape {

}

public class Circle implements Shape {

}

，我有一个 ApplicationModule ，它需要为 Rec 和 Circle 提供实例strong>：

and I have a ApplicationModule which needs to provides instances for both Rec and Circle:

@Module
public class ApplicationModule {
    private Shape rec;
    private Shape circle;

    public ApplicationModule() {
        rec = new Rectangle();
        circle= new Circle ();
    }

    @Provides
    public Shape provideRectangle() {
        return rec ;
    }

    @Provides
    public Shape provideCircle() {
        return circle;
    }
}

和 ApplicationComponent ：

@Component(modules = ApplicationModule.class)
public interface ApplicationComponent {
    Shape provideRectangle();
}

包含代码原样-无法编译。
错误说

with the code the way it is - it won't compile. error saying

错误：（33，20）错误：形状被绑定多次。

Error:(33, 20) error: Shape is bound multiple times.

这对我来说很有意义，因为该组件正试图找到 Shape 实例，它找到了其中两个，所以它不知道要返回哪个。

It makes sense to me that this can't be done, because the component is trying to find a Shape instance, and it finds two of them, so it doesn't know which one to return.

我的问题是-我该如何处理这个问题？

My question is - how can I handle this issue?

推荐答案

我最近在这篇文章中发布了这样一个问题的答案：

I recently post the answer to a question like this in this post :

Dagger 2：错误，而使用@Named

获取同一对象的多个实例您需要使用 @Named（ someName）在您的模块中像这样：

You need to use @Named("someName")in your module like this:

@Module
public class ApplicationModule {
private Shape rec;
private Shape circle;

public ApplicationModule() {
    rec = new Rectangle();
    circle= new Circle ();
}

@Provides
 @Named("rect")
public Shape provideRectangle() {
    return rec ;
}

@Provides
 @Named("circle")
public Shape provideCircle() {
    return circle;
}

}

然后在任何需要注入它们的地方只要写

Then wherever you need to inject them just write

@Inject
@Named("rect")
 Shape objRect;

它很有趣，但您必须以不同的方式在Kotlin中注入：

its funny but you have to inject in a different way in Kotlin:

@field:[Inject Named("rect")]
lateinit var objRect: Shape

这篇关于匕首2-两个提供相同界面的方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！