代码：
大体是一样的，修改了一些
依赖
implementation("androidx.lifecycle:lifecycle-extensions:2.2.0")
MainActivity
package com.example.geoquiz
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.View
import android.widget.Button
import android.widget.TextView
import android.widget.Toast
import androidx.lifecycle.ViewModelProviders
private const val KEY_INDEX = "index"
private const val KEY_SOCRE = "socre"
private const val KEY_BUTTONSTATUS="buttonStatus"
class MainActivity : AppCompatActivity() {
private lateinit var questionText: TextView
private lateinit var ture_button: Button
private lateinit var false_button: Button
private lateinit var last_button: Button
private lateinit var next_button: Button
private lateinit var score_button: Button
private val TAG="MainActivity"
private val quizViewModel: QuizViewModel by lazy {
ViewModelProviders.of(this)[QuizViewModel::class.java]
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val index= savedInstanceState?.getInt(KEY_INDEX,0)?:0
quizViewModel.index=index
questionText = findViewById(R.id.question)
ture_button = findViewById(R.id.ture_button)
false_button = findViewById(R.id.false_button)
last_button = findViewById(R.id.last_button)
next_button = findViewById(R.id.next_button)
next_button = findViewById(R.id.next_button)
score_button = findViewById(R.id.score_button)
updateQuestion()
//点击问题跳转下一题
questionText.setOnClickListener(View.OnClickListener {
quizViewModel.nextQuestion()
updateQuestion()
})
ture_button.setOnClickListener(View.OnClickListener {
quizViewModel.buttonStatus = false
checkAnswer(true)
closeButton()
})
false_button.setOnClickListener(View.OnClickListener {
quizViewModel.buttonStatus = false
checkAnswer(false)
closeButton()
})
last_button.setOnClickListener(View.OnClickListener {
openButton()
quizViewModel.lastQuestion()
updateQuestion()
})
next_button.setOnClickListener(View.OnClickListener {
openButton()
quizViewModel.nextQuestion()
updateQuestion()
})
score_button.setOnClickListener(View.OnClickListener {
settlementScore()
})
}
override fun onStart() {
super.onStart()
Log.e(TAG, "onStart")
}
override fun onResume() {
super.onResume()
Log.e(TAG, "onResume")
}
override fun onPause() {
super.onPause()
Log.e(TAG, "onPause")
}
override fun onSaveInstanceState(outState: Bundle) {
super.onSaveInstanceState(outState)
Log.e(TAG,"onSaveInstanceState")
//保存问题索引值
outState.putInt(KEY_INDEX,quizViewModel.index)
}
override fun onStop() {
super.onStop()
Log.e(TAG, "onStop")
}
override fun onDestroy() {
super.onDestroy()
Log.e(TAG, "onDestroy")
}
private fun updateQuestion() {
var textId = quizViewModel.questionIndex
questionText.setText(textId)
}
private fun checkAnswer(answer: Boolean) {
var questionanswer = quizViewModel.questionAnswer
if (answer == questionanswer) {
quizViewModel.score += 20
Toast.makeText(this, R.string.ture_toast, Toast.LENGTH_SHORT).show()
} else {
Toast.makeText(this, R.string.false_toast, Toast.LENGTH_SHORT).show()
}
}
private fun closeButton() {
if (!quizViewModel.buttonStatus) {
ture_button.isEnabled = quizViewModel.buttonStatus
false_button.isEnabled = quizViewModel.buttonStatus
}
}
private fun openButton() {
if (!quizViewModel.buttonStatus) {
ture_button.isEnabled = true
false_button.isEnabled = true
}
}
private fun settlementScore() {
//答完所有题结算成绩
if (quizViewModel.index == quizViewModel.listSize - 1) {
Toast.makeText(this, "得分为${
quizViewModel.score}", Toast.LENGTH_SHORT).show()
quizViewModel.score = 0
} else {
Toast.makeText(this, "题目没有答完哦", Toast.LENGTH_SHORT).show()
}
}
}
QuizViewModel
package com.example.geoquiz
import androidx.lifecycle.ViewModel
class QuizViewModel : ViewModel() {
var index = 0
private var questionList = listOf(
Question(R.string.question, true),
Question(R.string.question1, true),
Question(R.string.question2, true),
Question(R.string.question3, false),
Question(R.string.question4, false),
Question(R.string.question5, false)
)
var buttonStatus = true//按钮可以按
var score = 0
val listSize = questionList.size
val questionIndex: Int
get() = questionList[index].questionID
val questionAnswer: Boolean
get() = questionList[index].answer
fun nextQuestion() {
index = (index + 1) % questionList.size
}
fun lastQuestion() {
// if (index == 0) {
// index = questionList.size - 1
// } else {
// index -= 1
// }
index = if (index == 0) questionList.size - 1 else index - 1
}
}
Question
package com.example.geoquiz
import androidx.annotation.StringRes
data class Question(@StringRes val questionID: Int, val answer: Boolean) {
}
知识点
ViewModelProviders类提供了ViewModelProvider实例，调用ViewModelProviders.of(this)创建并返回一个关联了MainActivity的ViewModelProvider实例，ViewModelProvider会提供ViewModel实例给MainActivity
activity被销毁的两种情况：
- 用户结束使用activity
- 因设备配置发送改变时系统销毁
