android - Observe Kotlin 中的返回值

Question

如何从观察者返回一个值？

    val clockInAndOutTime = ClockInAndOutTime()
    clockInAndOutTime.id = 12
    longToast("Name " +displayName(clockInAndOutTime.id.toString()))

 private fun displayName(userId: String): String {

        var name = ""
        organizationViewModel.refreshList()
        organizationViewModel.organization.observe(
            this, Observer { resource ->
                resource?.data.let {
                    it?.forEach { organization ->
                        if (organization.user_id == userId) {
                            name = organization.user_name!!
                            Log.d(TAG, "name is $name")
                        }else{
                            Log.d(TAG,"not found")
                        }
                    }
                }
            }
        )
        return name
    }

在 displayName 函数中，我们可以得到名字，但是在 toast 中，Name总是显示为空。

Answer 1

你不能那样做。在你的 Observer 中调用一个函数

private fun displayName(userId: String, onNameFound: (String) -> Unit): String {

    var name = ""
    organizationViewModel.refreshList()
    organizationViewModel.organization.observe(
        this, Observer { resource ->
            resource?.data.let {
                it?.forEach { organization ->
                    if (organization.user_id == userId) {
                        name = organization.user_name!!
                        Log.d(TAG, "name is $name")
                        onNameFound(name)
                    }else{
                        Log.d(TAG,"not found")
                    }
                }
            }
        }
    )
    return name
}

然后将其称为

displayName(clockInAndOutTime.id.toString()) { longToast("Name $it") }