android - 我可以在循环中使用ArrayList ，map或hashmap作为表达式或语句来减少代码重复吗？

Question

我的菜单项将增加很多，因此我想知道我可以在表达式中使用Array，map或hashmap来减少重复。我现在有

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    // Handle item selection
    var messages: ArrayList<String>
    var timestamps: ArrayList<String>
    var linknames: ArrayList<String>
    var parsedData: ParsedData

    return when (item.itemId) {
        dataIdRead[0] -> {
            Thread(Runnable {
                parsedData = GetMessages(dataCity[0]).getParsedData()
                timestamps = parsedData.timestamps
                messages = parsedData.messages
                linknames = parsedData.linknames
                runOnUiThread {
                    rv_message_list.adapter =
                        MessageAdapter(messages, timestamps, linknames, this)
                    button.visibility = View.VISIBLE
                }
            }).start()
            true
        }

        dataIdRead[1] -> {
            Thread(Runnable {
                parsedData = GetMessages(dataCity[1]).getParsedData()
                timestamps = parsedData.timestamps
                messages = parsedData.messages
                linknames = parsedData.linknames
                runOnUiThread {
                    rv_message_list.adapter =
                        MessageAdapter(messages, timestamps, linknames, this)
                    button.visibility = View.VISIBLE
                }
            }).start()
            true
        }
        dataIdRead[2] -> {
            Thread(Runnable {
                parsedData = GetMessages(dataCity[2]).getParsedData()
                timestamps = parsedData.timestamps
                messages = parsedData.messages
                linknames = parsedData.linknames
                runOnUiThread {
                    rv_message_list.adapter =
                        MessageAdapter(messages, timestamps, linknames, this)
                    button.visibility = View.VISIBLE
                }
            }).start()
            true
        }
        else -> super.onOptionsItemSelected(item)

和

   val dataIdRead = arrayOf(R.id.helsinki, R.id.vantaa, R.id.espoo)
   val dataCity = arrayOf("helsinki", "vantaa", "espoo")

看起来像这样的东西

return when (item.itemId) {
        *some magic* -> {
            Thread(Runnable {
                parsedData = GetMessages(*some magic*).getParsedData()
                timestamps = parsedData.timestamps
                messages = parsedData.messages
                linknames = parsedData.linknames
                runOnUiThread {
                    rv_message_list.adapter =
                        MessageAdapter(messages, timestamps, linknames, this)
                    button.visibility = View.VISIBLE
                }
            }).start()
            true
        }
        else -> super.onOptionsItemSelected(item)

我已经尝试过forEach的示例，但是在开始行 return when (item.itemId) {等待表达式，但我并没有那么做。

Answer 1

您不需要为此循环。只需获取dataIdRead的索引。如果不是-1，则将该索引粘贴到dataCity中。

val index =  dataIdRead.indexOf(item.itemId) 
return if(index == -1) { 
     print("item not found")
     super.onOptionsItemSelected(item) }
else {
      Thread(Runnable {
            parsedData = GetMessages(dataCity[ index ]).getParsedData()
            timestamps = parsedData.timestamps
            messages = parsedData.messages
            linknames = parsedData.linknames
            runOnUiThread {
                rv_message_list.adapter =
                    MessageAdapter(messages, timestamps, linknames, this)
                button.visibility = View.VISIBLE
            }
        }).start()
        true
}