问Kotlin多重时间语句

EN

// my Kotlin function
// setting a specific state
private fun setState(num: Int) {
    Log.v(TAG, num.toString())
    // get the correct image id
    val imageId: Int? = when (num) {
        0 -> R.drawable.lemon_restart
        1 -> R.drawable.lemon_tree
        2 -> R.drawable.lemon_squeeze
        3 -> R.drawable.lemon_drink
        else -> null
    }
    // get the correct text to show
    val txtId: Int? = when (num) {
        0 -> R.string.txt_state_0
        1 -> R.string.txt_state_1
        2 -> R.string.txt_state_2
        3 -> R.string.txt_state_3
        else -> null
    }
    // get the correct content description for accessibility
    val contentDescriptionId: Int? = when (num) {
        0 -> R.string.lemon_restart_description
        1 -> R.string.lemon_tree_description
        2 -> R.string.lemon_squeeze_description
        3 -> R.string.lemon_drink_description
        else -> null
    }
    // setting the new stuff
    val imView: ImageView = findViewById(R.id.imageState)
    val txtView: TextView = findViewById(R.id.textOrder)
    txtView.text = getString(txtId!!)
    imView.setImageResource(imageId!!)
    imView.contentDescription = getString(contentDescriptionId!!)
}