《Android编程权威指南》之Android与MVC篇

data class Question(@StringRes val textResId: Int, val answer: Boolean)

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
        android:id="@+id/question_text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:padding="24dp"
        tools:text="@string/question_australia" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/true_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/true_button" />

        <Button
            android:id="@+id/false_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:text="@string/false_button" />
    </LinearLayout>

    <Button
        android:id="@+id/next_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/next_button" />
</LinearLayout>

string.xml

<resources>
    <string name="app_name">GeoQuiz</string>
    <string name="question_australia">Canberra is the capital of Australia.</string>
    <string name="true_button">True</string>
    <string name="false_button">False</string>
    <string name="next_button">Next</string>

    <string name="correct_toast">Correct!</string>
    <string name="incorrect_toast">Incorrect!</string>

    <string name="question_oceans">The Pacific Ocean is larger than the Atlantic Ocean.</string>
    <string name="question_mideast">The Suez Canal connects the Red Sea and the Indian Ocean.</string>
    <string name="question_africa">The source of the Nile River is in Egypt.</string>
    <string name="question_americas">The Amazon River is the longest river in the Americas.</string>
    <string name="question_asia">Lake Baikal is the world\'s oldest and deepest freshwater lake.</string>
</resources>

MainActivity.kt

class MainActivity : AppCompatActivity() {

    private lateinit var trueButton: Button
    private lateinit var falseButton: Button
    private lateinit var nextButton: Button
    private lateinit var questionTextView: TextView

    private val questionBank = listOf(
        Question(R.string.question_australia, true),
        Question(R.string.question_oceans, true),
        Question(R.string.question_mideast, false),
        Question(R.string.question_africa, false),
        Question(R.string.question_americas, true),
        Question(R.string.question_asia, true)
    )
    private var currentIndex = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        trueButton = findViewById(R.id.true_button)
        falseButton = findViewById(R.id.false_button)
        nextButton = findViewById(R.id.next_button)
        questionTextView = findViewById(R.id.question_text_view)

        trueButton.setOnClickListener { checkAnswer(true) }
        falseButton.setOnClickListener { checkAnswer(false) }
        nextButton.setOnClickListener {
            currentIndex = (currentIndex + 1) % questionBank.size
            updateQuestion()
        }
        updateQuestion()
    }

    /**
     * 更新问题
     */
    private fun updateQuestion() {
        val questionTextResId = questionBank[currentIndex].textResId
        questionTextView.setText(questionTextResId)
    }

    private fun checkAnswer(userAnswer: Boolean) {
        val correctAnswer = questionBank[currentIndex].answer
        val messageResId = if (userAnswer == correctAnswer) {
            R.string.correct_toast
        } else {
            R.string.incorrect_toast
        }
        Toast.makeText(this, messageResId, Toast.LENGTH_SHORT).show()
    }
} 

questionTextView.setOnClickListener {
            currentIndex = (currentIndex + 1) % questionBank.size
            updateQuestion()
        }

preButton.setOnClickListener {
            currentIndex = (currentIndex + questionBank.size - 1) % questionBank.size
            updateQuestion()
        }