Kotlin-在随机列表中获取新的项目索引

问题描述

我有一个选择题，每个答案有4个选择。在具有问题和选择的ArrayList中，将正确答案设置为正确选项的索引。我想打乱选择，但不确定如何确定正确答案的新索引。有什么想法吗？

问题对象

object ConstantsAnalysis {
        const val TOTAL_CORRECT: String = "total_correct"
        const val TOTAL_OPP: String = "total_opp"
        fun getQuestions3(): ArrayList<Questions3> {
            val questionList = ArrayList<Questions3>()
            val q1 = Questions3(1,null,"On a graph,the horizontal line along which data are plotted is the _____","y axis","x axis","origin","quadrant",2,R.string.Jones_1995,null)
questionList.addAll(listof(q1))
            questionList.shuffle()
            return questionList
        }
    }

数据类

data class Questions3(
    val id: Int,val image: Int?,val question: String,val option1: String,val option2: String,val option3: String,val option4: String,val correctAnswer: Int,val dialogBox: Int?,val dialogBox2: Int?)

随机选择

val ansorder = arrayOf(question.option1,question.option2,question.option3,question.option4)
        ansorder.shuffle()
        radio_button1.text = ansorder[0]
        radio_button2.text = ansorder[1]
        radio_button3.text = ansorder[2]
        radio_button4.text = ansorder[3]

检查答案选择

if (questions3!!.correctAnswer != mSelectedOptionPosition) {
//do x
}

编辑（由于correct answer是一个字符串，并且在改组answerView(questions3.correctAnswer,R.drawable.correct_option_border之后，索引会更改。

class QuestionsActivityAnalysis : AppCompatActivity(),View.OnClickListener {

    private var mCurrentPosition:Int = 1
    private var mQuestionsList:ArrayList<Questions3>? = null
    private var mSelectedOptionPosition:Int = 0
    private var mCorrectAnswers: Int = 0
    private var mSelectedOptionText: String? = null

private fun shuffle() {
        val question = mQuestionsList!![mCurrentPosition - 1]
        val ansorder = arrayOf(question.option1,question.option4)
        ansorder.shuffle()
        radio_button1.text = ansorder[0]
        radio_button2.text = ansorder[1]
        radio_button3.text = ansorder[2]
        radio_button4.text = ansorder[3]
    }

override fun onClick(v: View?) {
        when(v?.id){
            R.id.radio_button1 -> { selectedOptionView(radio_button1,1)
                mSelectedOptionText = radio_button1.text as String?
            }
            R.id.radio_button2 -> { selectedOptionView(radio_button2,2)
                mSelectedOptionText = radio_button2.text as String?
            }
            R.id.radio_button3 -> { selectedOptionView(radio_button3,3)
                mSelectedOptionText = radio_button3.text as String?
            }
            R.id.radio_button4 -> { selectedOptionView(radio_button4,4)
                mSelectedOptionText = radio_button4.text as String?
            }

R.id.btn_submit -> {
val questions3 = mQuestionsList?.get(mCurrentPosition - 1)
                    if (questions3!!.correctAnswer != mSelectedOptionText) {
} else {
                        mCorrectAnswers++
                    }
                    answerView(questions3.correctAnswer,R.drawable.correct_option_border)

private fun answerView(answer: Int,drawableView: Int) {
        when(answer){
            1 -> {
                radio_button1.background = ContextCompat.getDrawable(this,drawableView)
            }
            2 -> {
                radio_button2.background = ContextCompat.getDrawable(this,drawableView)
            }
            3 -> {
                radio_button3.background = ContextCompat.getDrawable(this,drawableView)
            }
            4 -> {
                radio_button4.background = ContextCompat.getDrawable(this,drawableView)
            }
        }
    }

解决方法

我真的建议仅创建一个像这样的数据类：

data class QuestionOption(val question:String,val isCorrect = false)

之后，您可以按照自己喜欢的任何方式进行随机播放，只需检查所选的QuestionOption是否将isCorrect设置为true。您会获得很多好处，逻辑也会变得更简单。

编辑：

为了更轻松地以这种方式声明问题：

通常，如果您在代码中添加问题，则只需要所需的必要代码。为此，您可以声明一个好的构造函数，也可以是一个将您的值基本上映射到构造函数的函数。就您而言，我会说

data class Questions3(
    val id: Int,val question: String,val option1: String,val option2: String,val option3: String,val correctOption: String,val image: Int?=null,val dialogBox1: Int?=null,val dialogBox2: Int?=null)

（请注意可选参数的最后位置，由于默认情况下它们为null，因此您也无需指定它们）

从某种意义上说，从理论上讲，您也可以（不是太干净，但很容易）只是将选项1-3和correctOption混洗，然后比较是否正确的Option String与选定的String相匹配。

否则，正如我所说，您始终可以创建用于映射内容的逻辑。在这里，您可以从构造函数映射到另一个构造函数，就像返回返回完成对象的函数一样。