我是kotlin和Android工作室的新手。我正在按照教程进行操作，一切顺利，直到我收到大量“未解决的参考错误”
我查看了有关此问题的其他人的帖子，但似乎没有任何帮助，因为我仍然收到多个错误
我试过了：
Android Studio 3.3.1 Build #AI-182.5107.16.33.5264788, built on January 28, 2019
JRE: 1.8.0_152-release-1248-b01 amd64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Windows 10 10.0我的代码
package e.lakal.tapfighter
import android.content.ContentValues.TAG
import android.os.Bundle
import android.os.CountDownTimer
import android.os.PersistableBundle
import android.support.design.widget.Snackbar
import android.support.v7.app.AppCompatActivity
import android.util.Log
import android.view.Menu
import android.view.MenuItem
import android.widget.Button
import android.widget.TextView
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
internal lateinit var tapmeButton: Button;
internal lateinit var GameScore: TextView;
internal lateinit var Timer: TextView;
internal var Score = 0
internal var gameStarted = false
internal lateinit var countDownTimer : CountDownTimer
internal val initalCountDown: Long = 60000;
internal val CountDownInterval: Long = 1000;
internal val TAG = MainActivity::class.java.simpleName
internal val timeLeftonTimer : Long = 6000
companion object {
private val SCORE_KEY ="SCORE_KEY"
private val TIME_LEFT_KEY = "TIME_LEFT_KEY"
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
Log.d(TAG, "On create called. Score is $Score")
setSupportActionBar(toolbar)
fab.setOnClickListener { view ->
Snackbar.make(view, "Replace with your own action",
Snackbar.LENGTH_LONG)
.setAction("Action", null).show()
}
tapmeButton = findViewById<Button>(R.id.tapmeButton)
GameScore = findViewById<TextView>(R.id.GameScore)
Timer = findViewById<TextView>(R.id.Timer)
GameScore.text = getString(R.string.YourScore, Score.toString())
tapmeButton.setOnClickListener{ view ->
incrementScore()
}
resetGame()
}
private fun resetGame(){
Score = 0
GameScore.text = getString(R.string.YourScore, Score.toString())
val initalTimeLeft = initalCountDown / 1000
Timer.text = getString(R.string.TimeLeft,
initalTimeLeft.toString())
countDownTimer = object: CountDownTimer(initalCountDown,
CountDownInterval) {
override fun onTick(millisUntilFinished: Long) {
val timeLeft = millisUntilFinished / 1000
Timer.text = getString(R.string.TimeLeft,
timeLeft.toString())
}
override fun onFinish() {
endGame()
}
}
gameStarted =false;
}
// Starts giving me problems here
}
private fun startGame(){
countDownTimer.start()
gameStarted
}
override fun onSaveInstanceState(outState: Bundle?,
outPersistentState: PersistableBundle?) {
super.onSaveInstanceState(outState, outPersistentState)
outState?.putInt(SCORE_KEY, Score)
outState?.putLong(TIME_LEFT_KEY, timeLeftonTimer)
countDownTimer.cancel()
Log.d(TAG,"onSaveInstanceState : Saving score : $Score & Saving
Time current $timeLeftonTimer")
}
override fun onDestroy(){
super.onDestroy()
Log.d(TAG, "onDestroy called.")
}
private fun endGame(){
Toast.makeText(this, getString(R.string.game_over_msg, Score.toString()), Toast.LENGTH_SHORT).show()
resetGame()
}
private fun incrementScore() {
if(!gameStarted){
startGame() }
Score++
val newScore = getString(R.string.YourScore, Score.toString())
GameScore.text = newScore
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
menuInflater.inflate(R.menu.menu_main, menu)
return true
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
return when (item.itemId) {
R.id.action_settings -> true
else -> super.onOptionsItemSelected(item)
}
}
}
logcat的
019-02-24 17:49:13.359 2003-6170/? E/WakeLock: GCM_HB_ALARM release
without a matched acquire!2019-02-24 17:49:13.450 1641-1769/?
I/WifiService: getConnectionInfo uid=10013
2019-02-24 17:49:58.235 1641-1769/? D/WificondControl: Scan result
ready event
2019-02-24 17:50:00.008 1641-1654/? E/memtrack: Couldn't load
memtrack module
2019-02-24 17:50:00.008 1641-1654/? W/android.os.Debug: failed to
get memory consumption info: -1
2019-02-24 17:50:00.016 1436-1454/? D/hwcomposer: hw_composer sent
6 syncs in 60s
2019-02-24 17:50:00.111 1443-1443/? I/boot-pipe: done populating
/dev/random
2019-02-24 17:50:15.532 1641-1658/? E/BatteryExternalStatsWorker:
modem info is invalid: ModemActivityInfo{ mTimestamp=0
mSleepTimeMs=0 mIdleTimeMs=0 mTxTimeMs[]=[0, 0, 0, 0, 0]
mRxTimeMs=0 mEnergyUsed=0}
编辑：通过在onCreate函数下移动onSaveInstanceState（）和onDestory来解决问题
在'//开始在这里给我带来问题'的下面，方法的范围是文件的根，而不是在类内。
所以，我重新格式化你的代码，我可以检查'未解决的参考错误'消失，不包括工具栏，工厂和R。**
试一试，注意结果。
package e.lakal.tapfighter
import android.content.ContentValues
import android.content.ContentValues.TAG
import android.os.Bundle
import android.os.CountDownTimer
import android.os.PersistableBundle
import android.util.Log
import android.view.Menu
import android.view.MenuItem
import android.widget.Button
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.appg.saltfactory.R
import com.google.android.material.snackbar.Snackbar
class MainActivity : AppCompatActivity() {
internal lateinit var tapmeButton: Button;
internal lateinit var GameScore: TextView;
internal lateinit var Timer: TextView;
internal var Score = 0
internal var gameStarted = false
internal lateinit var countDownTimer: CountDownTimer
internal val initalCountDown: Long = 60000;
internal val CountDownInterval: Long = 1000;
internal val TAG = MainActivity::class.java.simpleName
internal val timeLeftonTimer: Long = 6000
companion object {
private val SCORE_KEY = "SCORE_KEY"
private val TIME_LEFT_KEY = "TIME_LEFT_KEY"
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.main_activity)
Log.d(TAG, "On create called. Score is $Score")
setSupportActionBar(toolbar)
fab.setOnClickListener { view ->
Snackbar.make(
view, "Replace with your own action",
Snackbar.LENGTH_LONG
)
.setAction("Action", null).show()
}
tapmeButton = findViewById<Button>(R.id.tapmeButton)
GameScore = findViewById<TextView>(R.id.GameScore)
Timer = findViewById<TextView>(R.id.Timer)
GameScore.text = getString(R.string.YourScore, Score.toString())
tapmeButton.setOnClickListener { view ->
incrementScore()
}
resetGame()
}
private fun resetGame() {
Score = 0
GameScore.text = getString(R.string.YourScore, Score.toString())
val initalTimeLeft = initalCountDown / 1000
Timer.text = getString(
R.string.TimeLeft,
initalTimeLeft.toString()
)
countDownTimer = object : CountDownTimer(
initalCountDown,
CountDownInterval
) {
override fun onTick(millisUntilFinished: Long) {
val timeLeft = millisUntilFinished / 1000
Timer.text = getString(
R.string.TimeLeft,
timeLeft.toString()
)
}
override fun onFinish() {
endGame()
}
}
gameStarted = false;
}
// Starts giving me problems here
private fun startGame() {
countDownTimer.start()
gameStarted
}
override fun onSaveInstanceState(
outState: Bundle?,
outPersistentState: PersistableBundle?
) {
super.onSaveInstanceState(outState, outPersistentState)
outState?.putInt(SCORE_KEY, Score)
outState?.putLong(TIME_LEFT_KEY, timeLeftonTimer)
countDownTimer.cancel()
Log.d(
ContentValues.TAG, "onSaveInstanceState : Saving score : $Score & Saving Time current $timeLeftonTimer")
}
override fun onDestroy() {
super.onDestroy()
Log.d(ContentValues.TAG, "onDestroy called.")
}
private fun endGame() {
Toast.makeText(this, getString(R.string.game_over_msg, Score.toString()), Toast.LENGTH_SHORT).show()
resetGame()
}
private fun incrementScore() {
if (!gameStarted) {
startGame()
}
Score++
val newScore = getString(R.string.YourScore, Score.toString())
GameScore.text = newScore
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
menuInflater.inflate(R.menu.menu_main, menu)
return true
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
return when (item.itemId) {
R.id.action_settings -> true
else -> super.onOptionsItemSelected(item)
}
}
}
尝试将gradle版本从3.3.1更改为3.2.1
classpath 'com.android.tools.build:gradle:3.2.1'