未解决的Kotlin Android功能参考

Question

我的MainActivity中有以下onCreate功能。

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    var selected_answer = 0

    val btn_list = mutableListOf<ToggleButton>(button1, button2, button3, button4)

    for(i in btn_list){
        i.setOnClickListener{
            toggle_rest(btn_list.indexOf(i), btn_list)
            selected_answer = btn_list.indexOf(i)+1

        }
    }


    fun toggle_rest(toCheck : Int, btn_list : List<ToggleButton>){


        for (i in btn_list) {
            i.setChecked(btn_list.indexOf(i) == toCheck)

        }
    }
    question_txt.setText("Quiz will begin shortly!")
}

当我致电toggle_rest时，它会发出错误toggle_rest:Unresolved reference。

Answer 1

在使用代码之前，必须先定义toggle_rest函数，否则将获得 unresolve reference 编译错误：

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    var selected_answer = 0

    //Declare your function before you use
    fun toggle_rest(toCheck : Int, btn_list : List<ToggleButton>){
        for (i in btn_list) {
            i.setChecked(btn_list.indexOf(i) == toCheck)
        }
    }

    val btn_list = mutableListOf<ToggleButton>(button1, button2, button3, button4)

    for(i in btn_list){
        i.setOnClickListener{
            toggle_rest(btn_list.indexOf(i), btn_list)
            selected_answer = btn_list.indexOf(i)+1
        }
    }

    question_txt.setText("Quiz will begin shortly!")
}

Answer 2

您还可以在onCreate（）方法之外定义函数，如下所示。

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    var selected_answer = 0

    val btn_list = mutableListOf<ToggleButton>(button1, button2, button3, button4)

    for(i in btn_list){
        i.setOnClickListener{
            toggle_rest(btn_list.indexOf(i), btn_list)
            selected_answer = btn_list.indexOf(i)+1

        }
    }
    question_txt.setText("Quiz will begin shortly!")
}

fun toggle_rest(toCheck : Int, btn_list : List<ToggleButton>){


    for (i in btn_list) {
        i.setChecked(btn_list.indexOf(i) == toCheck)

    }
}

按照您的期望工作。