Kotlin

Question

我正在学习 android 开发者中心的教程。挑战之一是扩展教程掷骰子以包含 2 个骰子。我尝试创建我的骰子的第二个实例 var dice2 = Dice(6) 使用我为第一个模具所做的相同 class 定义。但是，两者 return 的值相同。所以我尝试为 Dice2 创建第二个 class 定义，并使用 `var dice2 = Dice2(6) 创建了一个实例。但我得到了相同的结果。以下是完整代码。

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val rollButton: Button = findViewById(R.id.button)
        rollButton.setOnClickListener { rollDice() }

        //roll the dice onLoad
        rollDice()
    }

    private fun rollDice() {

        //create two 6 sided die and rolls them
        val dice = Dice(6)
        val diceRoll = dice.roll()
        val dice2 = Dice2(6)
        val diceRoll2 = dice2.roll()

        //assign the ImageViews called imageView and imageView2 to the variables diceImage and diceImage2
        val diceImage: ImageView = findViewById(R.id.imageView)
        val diceImage2: ImageView = findViewById(R.id.imageView2)

        //update the die graphic based on the outcome of the dice roll
        //assigns the resource id to a variable called drawableResource
        val drawableResource = when(diceRoll) {
            1 -> R.drawable.dice_1
            2 -> R.drawable.dice_2
            3 -> R.drawable.dice_3
            4 -> R.drawable.dice_4
            5 -> R.drawable.dice_5
            else -> R.drawable.dice_6
        }
        /* do the same for the 2nd die */
        val drawableResource2 = when(diceRoll2) {
            1 -> R.drawable.dice_1
            2 -> R.drawable.dice_2
            3 -> R.drawable.dice_3
            4 -> R.drawable.dice_4
            5 -> R.drawable.dice_5
            else -> R.drawable.dice_6
        }
        /*Update the die image source based on the variable
        convert the die roll results from int to string and update the content description for
        the die image
         */
        diceImage.setImageResource(drawableResource)
        diceImage.contentDescription = diceRoll.toString()
        diceImage2.setImageResource(drawableResource)
        diceImage2.contentDescription = diceRoll2.toString()
    }
}

//create a class for an object called Dice & defines a roll function with random number
class Dice(private val numSides: Int) {

    fun roll(): Int {
        return (1..numSides).random()
    }
}
class Dice2(private val numSides: Int) {

    fun roll(): Int {
        return (1..numSides).random()
    }
}

非常感谢任何帮助。

Answer 1

您似乎在这一行中犯了错误：

diceImage2.setImageResource(drawableResource)

应该是：

diceImage2.setImageResource(drawableResource2)

Answer 2

尝试 diceImage2.setImageResource(drawableResource2) 而不是 diceImage2.setImageResource(drawableResource)。但更好：

你绝对不需要Dice2；像原来一样使用 val dice2 = Dice(6)，甚至再次使用 val diceRoll2 = dice.roll()。

如果你做了一个函数，你甚至可以避免犯那个错误的机会

fun showDiceResult(viewId: Int, rollResult: Int) {
    // get view by id
    // set image resource
    // set content description
}

然后调用了两次

showDiceResult(R.id.imageView, diceRoll)
showDiceResult(R.id.imageView2, diceRoll2)

Kotlin - 掷 2 个骰子，returns 每次两个骰子的值相同

Kotlin - Rolling 2 dice, returns the same value for both dice every time

dice