创建一个具有Int的BehaviourSubject [英] Creating a BehaviourSubject with an Int

问题描述

如何创建带有Int的此Subject的实例:

How can I create an instance of this Subject with an Int:

class NonNullableBehaviourSubject<T : Any>(defaultValue: T) : Subject<T>() {
   private val behaviourSubject = BehaviorSubject.createDefault<T>(defaultValue)
}

然后我像这样创建NonNullableBehaviourSubject的实例:

I then create an instance of NonNullableBehaviourSubject like this:

val emailValidationSubject = NonNullableBehaviourSubject(Int)

但是随后我得到了一个编译错误:

But I then get a compile error using this:

emailValidationSubject.onNext(error?.errorResId)

我得到的编译错误是:

Required: Companion.Int
Found: Int?

此外，Int不能为空.但是，NonNullableBehaviourSubject确实定义了可为空的参数.

Also, Int must not be nullable. Yet, NonNullableBehaviourSubject does define a nullable parameter.

推荐答案

您的error对象具有可为空的类型，并且您对其使用了安全调用(?.)，因此整个表达式都是可为空的. 要使值不可为空，您可以断言值不为空(如果error为null，error!!.errorResId将崩溃，如果整个表达式为null，则error?.errorResId!!将崩溃)或为null情况提供后备值((error ?: DEFAULT_ERROR).errorResId或error?.errorResId ?: DEFAULT_ERROR_RES).

Your error object has nullable type, and you use safe call (?.) on it, so the whole expression is nullable. To make the value non-nullable you can either assert value is not null (error!!.errorResId will crash if error is null, error?.errorResId!! will crash if the whole expression is null) or provide the fallback value for null case ((error ?: DEFAULT_ERROR).errorResId or error?.errorResId ?: DEFAULT_ERROR_RES).

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