如果没有@Provides注释的方法，则无法提供Dagger AndroidInjector [英] Dagger AndroidInjector cannot be provided without an @Provides-annotated method

问题描述

我已经通过MVP模式完成了Android项目MainActivity.因此，在MainPresenter中，我想注入一个动态String，然后将其填充到TextView中，例如:

I've done my Android projects MainActivity by means of the MVP pattern. So in my MainPresenter I want to inject a dynamic String, which then shall populate a TextView for instance:

class MyMainPresenter @Inject constructor(@StringForTextView dynamicString : String ) 

而StringForTextView注释限定符定义为:

whereas the StringForTextView annotation qualifier is defined as:

import javax.inject.Qualifier
@Qualifier
@MustBeDocumented
@Retention(AnnotationRetention.RUNTIME)
annotation class StringForTextView

然后我也有我的界面:

interface DynamicString {
    @NonNull fun getDynamicString() : String
}

实现为:

data class SimpleDynamicString(val dynString: String) : DynamicString {
    override fun getDynamicString(): String { return dynString }
}

然后在我的模块中:

@Provides
@StringForTextView
static DynamicString provideDynamicString(Application application)
{
    return new SimpleDynamicString(application.getString(R.string.example_string));
}

问题是，我得到一个错误

The problem is, that I get an error

错误:(51，2)错误:[dagger.android.AndroidInjector.inject(T)] @ com.ralf.example.injection.qualifiers.StringForTextView 如果没有@Provides注释，则无法提供java.lang.String 方法.

Error:(51, 2) error: [dagger.android.AndroidInjector.inject(T)] @com.ralf.example.injection.qualifiers.StringForTextView java.lang.String cannot be provided without an @Provides-annotated method.

我想念什么?

推荐答案

您正在提供DynamicString，同时期望构造函数中有常规的String.您也应该在其中使用DynamicString:

You're providing a DynamicString while expecting a regular String in the constructor. You should use DynamicString there as well:

class MyMainPresenter @Inject constructor(
    @StringForTextView dynamicString: DynamicString
)

此外，您可能希望通过将其设为val的属性来保留该注入的值.

Also, you might want to hols on to that injected value by making it a property with val.

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