Android Kotlin足球问答应用IndexOutOfBoundsException崩溃问题

问题概述 #

使用Kotlin开发Android足球问答应用，功能为展示球员图片并提供四个包含正确答案的选项按钮，要求每次启动生成新题目与不同错误选项。但应用在从MainActivity跳转至QuizActivity时或点击选项按钮时频繁崩溃，报错IndexOutOfBoundsException（例如：Index: 7, Size:6）。

错误日志 #

FATAL EXCEPTION: main
Process: com.example.footballquizapp, PID: 8219
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.footballquizapp/com.example.footballquizapp.QuizActivity}: java.lang.IndexOutOfBoundsException: Index: 7, Size: 6
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3162)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3305)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1993)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:216)
at android.app.ActivityThread.main(ActivityThread.java:7266)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:975)
Caused by: java.lang.IndexOutOfBoundsException: Index: 7, Size: 6
at java.util.ArrayList.get(ArrayList.java:437)
at com.example.footballquizapp.QuizActivity.generateQuestion(QuizActivity.kt:58)
at com.example.footballquizapp.QuizActivity.onCreate(QuizActivity.kt:37)
at android.app.Activity.performCreate(Activity.java:7353)
at android.app.Activity.performCreate(Activity.java:7344)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1275)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3142)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3305) 
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1993) 
at android.os.Handler.dispatchMessage(Handler.java:106) 
at android.os.Looper.loop(Looper.java:216) 
at android.app.ActivityThread.main(ActivityThread.java:7266) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:975)

问题根源 #

从错误日志可见，崩溃发生在generateQuestion方法中访问imageList[index]时。查看代码发现：

• playerList包含8个球员名称，但imageList仅添加了6个图片资源，两者数量不一致
• 当随机生成的index为6或7时，imageList没有对应索引的元素，直接触发数组越界异常

早期版本中btnWithCorrectAnswer方法每次调用都会重新生成题目，也会导致索引越界，虽已修复，但核心的列表数量不匹配问题未解决。

修复方案 #

1. 对齐球员名称与图片资源数量 #

选择以下两种方式之一：

• 补全图片资源：为Josua Kimmich和David Alaba添加对应的图片资源，并更新imageList：

private fun initializeViewsAndLists() {
    // ... 其他视图初始化
    imageList = ArrayList<Int>()
    imageList.add(R.drawable.neymar)
    imageList.add(R.drawable.ronaldo)
    imageList.add(R.drawable.messi)
    imageList.add(R.drawable.mueller)
    imageList.add(R.drawable.mbappe)
    imageList.add(R.drawable.robben)
    imageList.add(R.drawable.kimmich) // 添加对应图片
    imageList.add(R.drawable.alaba)   // 添加对应图片
}

• 移除无图片的球员：从playerList中删除没有对应图片的球员：

private fun initializeViewsAndLists() {
    // ... 其他视图初始化
    playerList = ArrayList<String>()
    playerList.add("Neymar Junior")
    playerList.add("Cristiano Ronaldo")
    playerList.add("Lionel Messi")
    playerList.add("Thomas Müller")
    playerList.add("Killian Mbappe")
    playerList.add("Arian Robben")
    // 移除无对应图片的球员
    // playerList.add("Josua Kimmich")
    // playerList.add("David Alaba")
}

2. 使用数据类封装球员数据（推荐） #

通过数据类将球员名称与图片资源绑定，从根源避免列表不同步问题：

// 定义球员数据类
data class Player(val name: String, val imageRes: Int)

class QuizActivity : AppCompatActivity() {
    // ... 其他视图变量
    lateinit var players: List<Player>

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_quiz)
        initializeViewsAndLists()
        val question = generateQuestion()
        val correctPlayer = question.first
        val options = question.second

        btnFirstAns.text = options[0]
        btnSecondAns.text = options[1]
        btnThirdAns.text = options[2]
        btnFourthAns.text = options[3]

        imageView.setImageResource(correctPlayer.imageRes)

        // 设置点击事件
        btnFirstAns.setOnClickListener { checkAnswer(btnFirstAns.text.toString(), correctPlayer.name) }
        btnSecondAns.setOnClickListener { checkAnswer(btnSecondAns.text.toString(), correctPlayer.name) }
        btnThirdAns.setOnClickListener { checkAnswer(btnThirdAns.text.toString(), correctPlayer.name) }
        btnFourthAns.setOnClickListener { checkAnswer(btnFourthAns.text.toString(), correctPlayer.name) }
    }

    fun generateQuestion(): Pair<Player, List<String>> {
        val correctPlayer = players.random()
        val wrongAnswers = players.filter { it != correctPlayer }.map { it.name }.shuffled().take(3)
        val options = (wrongAnswers + correctPlayer.name).shuffled()
        return Pair(correctPlayer, options)
    }

    private fun initializeViewsAndLists() {
        // ... 视图初始化
        players = listOf(
            Player("Neymar Junior", R.drawable.neymar),
            Player("Cristiano Ronaldo", R.drawable.ronaldo),
            Player("Lionel Messi", R.drawable.messi),
            Player("Thomas Müller", R.drawable.mueller),
            Player("Killian Mbappe", R.drawable.mbappe),
            Player("Arian Robben", R.drawable.robben),
            Player("Josua Kimmich", R.drawable.kimmich),
            Player("David Alaba", R.drawable.alaba)
        )
    }

    // ... 其他方法保持不变
}

3. 优化正确按钮查找逻辑 #

在生成题目时直接记录正确选项的文本，避免重复遍历按钮：

// 可以在类中添加变量记录当前正确选项文本
lateinit var currentCorrectAnswer: String

// 在onCreate中赋值
currentCorrectAnswer = correctPlayer.name

// 简化btnWithCorrectAnswer方法
fun btnWithCorrectAnswer(): Button? {
    return when(currentCorrectAnswer) {
        btnFirstAns.text -> btnFirstAns
        btnSecondAns.text -> btnSecondAns
        btnThirdAns.text -> btnThirdAns
        btnFourthAns.text -> btnFourthAns
        else -> null
    }
}

内容的提问来源于stack exchange，提问作者Jakob Gabriel