kotlin snackbar的函数扩展在fragment中不起作用

wvt8vs2t 于 2023-05-01 发布在 Kotlin

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我有这些View函数扩展：

fun View.showSnackbar(msgId: Int, length: Int) {
    showSnackbar(context.getString(msgId), length)
}

fun View.showSnackbar(msg: String, length: Int) {
    showSnackbar(msg, length, null, {})
}

fun View.showSnackbar(
    msgId: Int,
    length: Int,
    actionMessageId: Int,
    action: (View) -> Unit
) {
    showSnackbar(context.getString(msgId), length, context.getString(actionMessageId), action)
}

fun View.showSnackbar(
    msg: String,
    length: Int,
    actionMessage: CharSequence?,
    action: (View) -> Unit
) {
    val snackbar = Snackbar.make(this, msg, length)
    if (actionMessage != null) {
        snackbar.setAction(actionMessage) {
            action(this)
        }.show()
    }
}

我试图在我的片段中使用它，但Snackbar不显示。它没有崩溃，只是没有显示出来。但是，我的showSnackbar2()工作。以下是我在片段中使用它的方式：

class AddressesFragment : Fragment() {
    private lateinit var binding: FragmentAddressesBinding

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentAddressesBinding.inflate(inflater, container, false)
        binding.buttonSnackbar.setOnClickListener {view ->
            //showSnackbar1() // DOES NOT WORK!!
            showSnackbar2()
        }
        return binding.root
    }

    fun showSnackbar1() {
        binding.buttonSnackbar.showSnackbar(
            R.string.location_permission_granted,
            Snackbar.LENGTH_SHORT
        )
    }

    fun showSnackbar2() {
        val view = activity?.findViewById(android.R.id.content) as View
        Snackbar.make(
            view,
            R.string.location_permission_granted,
            Snackbar.LENGTH_SHORT
        ).show()
    }
}

如何修复我的函数扩展，使showSnackbar1()工作？

kotlin

来源：https://stackoverflow.com/questions/76135698/function-extension-of-snackbar-does-not-work-in-fragment

2条答案

按热度按时间

vc6uscn91#

您的Snackbar未显示，因为您正在检查if (actionMessage != null)。如果actionMessage == null，则不会显示Snackbar。请查看下面的详细说明：

fun View.showSnackbar(msgId: Int, length: Int) { // when you called showSnackbar1() this method was called.
    showSnackbar(context.getString(msgId), length)
}

fun View.showSnackbar(msg: String, length: Int) { // Then it goes here with some msg: String and length: Int you passed from the method above
    showSnackbar(msg, length, null, {})
}

fun View.showSnackbar(
    msg: String, // msg from context.getString(msgId)
    length: Int, // Length you passed from your fragment
    actionMessage: CharSequence?, // !!! this param is NULL, because you passed NULL
    action: (View) -> Unit
) {
    val snackbar = Snackbar.make(this, msg, length)
    if (actionMessage != null) { // !!! since actionMessage is null, this method is not being called
        snackbar.setAction(actionMessage) {
            action(this)
        }.show()
    }
}

因此，您需要在最后一个方法中传递action message，以显示您的Snackbar。

赞(0）回复(0）举报 2023-05-01

42fyovps2#

此扩展功能起作用。它扩展View对象并调用Snackbar对象：

fun View.showSnackbar(msg: String,
                      length: Int,
                      actionMessage: CharSequence?,) {
    Snackbar.make(this, msg, length).show()
}

然后按如下方式使用：

val view = this.findViewById(android.R.id.content) as View
view.showSnackbar("Hi", Snackbar.LENGTH_LONG, null)

// Or
binding.buttonSnackbar.showSnackbar("Hi", Snackbar.LENGTH_LONG, null)

赞(0）回复(0）举报 2023-05-01

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kotlin snackbar的函数扩展在fragment中不起作用

2条答案

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