Kotlin - 以编程方式创建的 Spinner 箭头丢失

Question

以编程方式创建Spinner 后，通常位于右侧的下拉箭头由于某种原因没有出现。为什么箭头不见了，怎么显示？

        spinnerItems = arrayOf(
            "Cathedral of the Intercession of the Most Holy Theotokos on the Moat",
            "Ferapontov Monastery",
            "Historic Monuments of Novgorod and Surroundings",
            "Golden Mountains of Altai",
            "Historic Centre of Saint Petersburg and Related Groups of Monuments",
            "Bogoroditse-Smolensky Monastery",
            "White Monuments of Vladimir and Suzdal"
        )

        val mySpinner =
            Spinner(view!!.context, null, android.R.style.Widget_Material_Spinner, Spinner.MODE_DROPDOWN)

        val arrayAdapter = ArrayAdapter(view!!.context, android.R.layout.simple_dropdown_item_1line, spinnerItems)
        arrayAdapter.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line)

        mySpinner.adapter = arrayAdapter

        mFrameLayout.addView(mySpinner)

Answer 1

这是因为您为微调器选择的样式

android.R.style.Widget_Material_Spinner

与默认行为不同，此样式中不包含箭头。您需要将其替换为其他样式或自行添加箭头。

val mySpinner = Spinner(
        ContextThemeWrapper(this, R.style.Widget_AppCompat_Spinner_Underlined),
        null,
        0,
        Spinner.MODE_DROPDOWN
    )

试试这个