Kotlin编写背单词app,要求有背单词功能，生词本，已背单词表，查单词功能

好的，以下是一个简单的Kotlin代码示例，实现了背单词app的基本功能：

import java.util.*

class Word(val word: String, val meaning: String, var isLearned: Boolean = false)

class WordList(words: List<Word>) {
    private val allWords: MutableList<Word> = words.toMutableList()
    private val learnedWords: MutableList<Word> = mutableListOf()
    private val newWords: MutableList<Word> = allWords.filter { !it.isLearned }.toMutableList()

    fun getNewWord(): Word? {
        if (newWords.isEmpty()) {
            return null
        }
        val index = Random().nextInt(newWords.size)
        return newWords[index]
    }

    fun addNewWord(word: Word) {
        allWords.add(word)
        newWords.add(word)
    }

    fun markAsLearned(word: Word) {
        word.isLearned = true
        learnedWords.add(word)
        newWords.remove(word)
    }

    fun getAllWords(): List<Word> {
        return allWords
    }

    fun getLearnedWords(): List<Word> {
        return learnedWords
    }

    fun getNewWords(): List<Word> {
        return newWords
    }
}

class Dictionary {
    private val words: MutableMap<String, String> = mutableMapOf(
        "apple" to "苹果",
        "banana" to "香蕉",
        "cherry" to "樱桃",
        "dog" to "狗",
        "elephant" to "大象"
    )

    fun lookup(word: String): String? {
        return words[word]
    }
}

class WordApp {
    private val dictionary = Dictionary()
    private val wordList = WordList(listOf(
        Word("apple", "苹果"),
        Word("banana", "香蕉"),
        Word("cherry", "樱桃")
    ))

    fun start() {
        while (true) {
            showMainMenu()
            val choice = readLine()?.toIntOrNull() ?: continue
            when (choice) {
                1 -> learnNewWord()
                2 -> reviewWords()
                3 -> showWordList()
                4 -> lookupWord()
                5 -> break
            }
        }
    }

    private fun showMainMenu() {
        println("""
            请选择操作：
            1. 学习新单词
            2. 复习已学单词
            3. 查看单词列表
            4. 查询单词意思
            5. 退出程序
        """.trimIndent())
    }

    private fun learnNewWord() {
        val newWord = wordList.getNewWord()
        if (newWord == null) {
            println("没有新单词了")
            return
        }
        println("请背诵单词：${newWord.word}")
        println("按任意键查看单词意思")
        readLine()
        println("单词意思：${newWord.meaning}")
        println("是否已经掌握这个单词？（y/n）")
        val choice = readLine()?.toLowerCase() ?: "n"
        if (choice == "y") {
            wordList.markAsLearned(newWord)
            println("已经掌握了这个单词！")
        }
    }

    private fun reviewWords() {
        val learnedWords = wordList.getLearnedWords()
        if (learnedWords.isEmpty()) {
            println("还没有学习过任何单词")
            return
        }
        println("已学单词列表：")
        learnedWords.forEach { println("${it.word} - ${it.meaning}") }
    }

    private fun showWordList() {
        val allWords = wordList.getAllWords()
        if (allWords.isEmpty()) {
            println("还没有学习过任何单词")
            return
        }
        println("单词列表：")
        allWords.forEach { println("${it.word} - ${it.meaning}") }
    }

    private fun lookupWord() {
        println("请输入要查询的单词：")
        val word = readLine()?.toLowerCase() ?: return
        val meaning = dictionary.lookup(word)
        if (meaning == null) {
            println("没有找到这个单词")
        } else {
            println("$word 的意思是 $meaning")
        }
    }
}

fun main() {
    WordApp().start()
}

这个app中，`Word`类表示一个单词，其中包含单词本身、意思和是否已经被学习过。`WordList`类表示一个单词列表，其中包含所有的单词、已经学习过的单词和还没有学习过的单词。`Dictionary`类表示一个简单的单词词典，可以根据单词查找意思。`WordApp`类是整个应用程序的入口，通过命令行界面提供了背单词、复习单词、查看单词列表、查询单词意思等功能。