android - NoSuchMethodException 试图实例化 ViewModel

Question

我正在尝试实例化我的 View 模型，但出现此错误

Caused by: java.lang.NoSuchMethodException: [class com.test.domain.PostUserTokenImpl] at java.lang.Class.getConstructor0(Class.java:2327) at java.lang.Class.getConstructor(Class.java:1725) at com.test.presentation.viewmodel.LoginVMFactory.create(LoginVMFactory.kt:13)

我尝试做一个持有和接口(interface)的 ViewModel 实例

看法

private val viewModel by lazy { ViewModelProviders.of(this, LoginVMFactory(PostUserTokenImpl(UserRepoImpl()))).get(LoginViewModel::class.java) }

登录VMFactory

class LoginVMFactory(private val useCase: PostUserTokenImpl):ViewModelProvider.Factory {

    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
        return modelClass.getConstructor(PostUserTokenImpl::class.java).newInstance(useCase)
    }
}

登录 View 模型

class LoginViewModel(private val useCase: PostUserToken): ViewModel() {
 ...
}

PostUserToken

interface PostUserToken {

    suspend fun postUserToken(user: User): Resource<Boolean>
}

PostUserTokenImpl

class PostUserTokenImpl(private val repo: UserRepo): PostUserToken {

   override suspend fun postUserToken(user:User):Resource<Boolean> = repo.saveUserToken(user)

}

知道为什么会这样吗？我怀疑这可能是因为我们不能用我们的 View 模型的接口(interface)实例化？

Answer 1

将我的实现更改为

class LoginVMFactory(private val useCase: PostUserToken):ViewModelProvider.Factory {

    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
        return modelClass.getConstructor(PostUserToken::class.java).newInstance(useCase)
    }
}

然后在我看来

private val viewModel by lazy { ViewModelProviders.of(this, LoginVMFactory(PostUserTokenImpl(UserRepoImpl()))).get(LoginViewModel::class.java) }