相同的值会触发 LiveDate 中的事件吗？

Question

代码A和图片A来自文章LiveData with SnackBar, Navigation and other events (the SingleLiveEvent case)。

作者告诉我"Trigger the event by setting a new Event as a new value"，我觉得应该是"Trigger the event by setting a new Event as any value"吧？

例如，

第 1 步：用户单击主 Activity 中带有代码 userClicksOnButton("StartDetails") 的按钮，详细信息 Activity 将启动。

第 2 步：用户按下返回，回到 master activity

第三步：用户再次点击代码userClicksOnButton("StartDetails")的masterActivity中的按钮，DetailsActivity将重新开始。

对吗？

代码A

class ListViewModel : ViewModel {
    private val _navigateToDetails = MutableLiveData<Event<String>>()

    val navigateToDetails : LiveData<Event<String>>
        get() = _navigateToDetails


    fun userClicksOnButton(itemId: String) {
        _navigateToDetails.value = Event(itemId)  // Trigger the event by setting a new Event as a new value
    }
}

open class Event<out T>(private val content: T) {

    var hasBeenHandled = false
        private set // Allow external read but not write

    /**
     * Returns the content and prevents its use again.
     */
    fun getContentIfNotHandled(): T? {
        return if (hasBeenHandled) {
            null
        } else {
            hasBeenHandled = true
            content
        }
    }

    /**
     * Returns the content, even if it's already been handled.
     */
    fun peekContent(): T = content
}

myViewModel.navigateToDetails.observe(this, Observer {
    it.getContentIfNotHandled()?.let { // Only proceed if the event has never been handled
        startActivity(DetailsActivity...)
    }
})

图片A

Answer 1

您对数据有两种不同的约束。

LiveData 向活跃的观察者发出每次更新，但事件本身是有状态的。因此需要 new 事件作为新的 LiveData 值。 itemId 可以是任何值，但注释没有引用它。

Trigger the event by setting a new Event as [a new] value

相同的值会触发 LiveDate 中的事件吗？

Will the same value trigger the event in LiveDate?

kotlin

android-jetpack