我需要快速删除此错误，所以请帮助我。
此代码是SongsPlayingFragment＆amp;的代码。错误在日志部分下给出。
我正在尝试构建音乐播放器应用。每当我打开应用程序＆amp;点击播放屏幕打开的任何歌曲＆amp;应用程序崩溃。
日志发出了一个我无法理解的类型转换错误。
任何帮助都得到高度赞赏
代码： -
package com.vikanshu.echo.Fragments
import android.app.Activity
import android.content.Context
import android.media.AudioManager
import android.media.MediaPlayer
import android.net.Uri
import android.os.Bundle
import android.os.Handler
import android.support.v4.app.Fragment
import android.support.v7.widget.DialogTitle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageButton
import android.widget.SeekBar
import android.widget.TextView
import com.vikanshu.echo.CurrentSongHelper
import com.vikanshu.echo.R
import com.vikanshu.echo.SongsDataType
import kotlinx.android.synthetic.main.fragment_song_playing.*
import java.util.*
import java.util.concurrent.TimeUnit
class SongPlayingFragment : Fragment() {
var myActivity: Activity ?= null
var mediaPlayer: MediaPlayer ?= null
var songName: TextView ?= null
var artistName: TextView ?= null
var seekBar : SeekBar ?= null
var startTime: TextView ?= null
var stopTime: TextView ?= null
var playPause: ImageButton ?= null
var previousSong: ImageButton ?= null
var nextSong: ImageButton ?= null
var loopSong: ImageButton ?= null
var shuffleSongs: ImageButton ?= null
var currentSongHelperObject: CurrentSongHelper ?= null
var currentPosition: Int = 0
var fetchSongs: ArrayList<SongsDataType> ?= null
var updateSongTime = object : Runnable{
override fun run() {
val getCurrent = mediaPlayer?.currentPosition
startTime?.setText(String.format("%d:%d",
TimeUnit.MILLISECONDS.toMinutes(getCurrent?.toLong() as Long),
TimeUnit.MILLISECONDS.toSeconds(getCurrent?.toLong() as Long) -
TimeUnit.MILLISECONDS.toSeconds(TimeUnit.MILLISECONDS.toMinutes(getCurrent?.toLong() as Long))
))
Handler().postDelayed(this,1000)
}
}
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
var view = inflater!!.inflate(R.layout.fragment_song_playing, container, false)
songName = view?.findViewById(R.id.songName)
artistName = view?.findViewById(R.id.songArtist)
seekBar = view?.findViewById(R.id.seekBar)
startTime = view?.findViewById(R.id.startTime)
stopTime = view?.findViewById(R.id.endTime)
playPause = view?.findViewById(R.id.playPauseButton)
previousSong = view?.findViewById(R.id.playPreviousButton)
nextSong = view?.findViewById(R.id.playNextButton)
loopSong = view?.findViewById(R.id.loopButton)
shuffleSongs = view?.findViewById(R.id.shuffleButton)
return view
}
override fun onAttach(context: Context?) {
super.onAttach(context)
myActivity = context as Activity
}
override fun onAttach(activity: Activity?) {
super.onAttach(activity)
myActivity = activity
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
currentSongHelperObject = CurrentSongHelper()
currentSongHelperObject?.isPlaying = true
currentSongHelperObject?.isLoop = false
currentSongHelperObject?.isShuffle = false
var path: String ?= null
var _songTitle: String ?= null
var _songID: Long ?= null
var _songArtist: String ?= null
try {
path = arguments.getString("path")
_songArtist = arguments.getString("songArtist")
_songTitle = arguments.getString("songTitle")
_songID = arguments.getInt("songID").toLong()
currentSongHelperObject?.songPath = path
currentSongHelperObject?.songArtist = _songArtist
currentSongHelperObject?.songId = _songID
currentSongHelperObject?.songTitle = _songTitle
currentPosition =arguments.getInt("songPosition")
fetchSongs = arguments.getParcelableArrayList("songData")
currentSongHelperObject?.currentPosition = currentPosition
updateTextViews(currentSongHelperObject?.songTitle as String,currentSongHelperObject?.songArtist as String)
}catch (e: Exception){
e.printStackTrace()
}
mediaPlayer = MediaPlayer()
mediaPlayer?.setAudioStreamType(AudioManager.STREAM_MUSIC)
try {
mediaPlayer?.setDataSource(myActivity,Uri.parse(path))
}catch (e: Exception){
e.printStackTrace()
}
mediaPlayer?.start()
processInformation(mediaPlayer as MediaPlayer)
if(currentSongHelperObject?.isPlaying as Boolean){
playPause?.setBackgroundResource(R.drawable.pause_icon)
}else{
playPause?.setBackgroundResource(R.drawable.play_icon)
}
mediaPlayer?.setOnCompletionListener {
onSongComplete()
}
clickHandler()
}
fun onSongComplete(){
if(currentSongHelperObject?.isShuffle as Boolean){
playNext("PlayShuffle")
currentSongHelperObject?.isPlaying = true
}else{
if (currentSongHelperObject?.isLoop as Boolean){
currentSongHelperObject?.isPlaying = true
var nextSong = fetchSongs?.get(currentPosition)
currentSongHelperObject?.songTitle = nextSong?.songTittle
currentSongHelperObject?.songPath = nextSong?.songData
currentSongHelperObject?.songId = nextSong?.songId as Long
currentSongHelperObject?.currentPosition = currentPosition
updateTextViews(currentSongHelperObject?.songTitle as String,currentSongHelperObject?.songArtist as String)
mediaPlayer?.reset()
try {
mediaPlayer?.setDataSource(myActivity,Uri.parse(currentSongHelperObject?.songPath))
mediaPlayer?.prepare()
mediaPlayer?.start()
processInformation(mediaPlayer as MediaPlayer)
}catch (e: Exception){
e.printStackTrace()
}
}else{
playNext("playNextNormal")
currentSongHelperObject?.isPlaying = true
}
}
}
fun clickHandler() {
shuffleButton?.setOnClickListener({
if(currentSongHelperObject?.isShuffle as Boolean){
shuffleButton?.setBackgroundResource(R.drawable.shuffle_white_icon)
currentSongHelperObject?.isShuffle = false
}else{
currentSongHelperObject?.isShuffle = true
currentSongHelperObject?.isLoop = false
shuffleSongs?.setBackgroundResource(R.drawable.shuffle_icon)
loopButton?.setBackgroundResource(R.drawable.loop_white_icon)
}
})
loopButton?.setOnClickListener({
if(currentSongHelperObject?.isLoop as Boolean) {
currentSongHelperObject?.isLoop = false
loopButton?.setBackgroundResource(R.drawable.loop_white_icon)
}else{
currentSongHelperObject?.isLoop = true
currentSongHelperObject?.isLoop = false
loopButton?.setBackgroundResource(R.drawable.loop_icon)
}
})
playPauseButton?.setOnClickListener({
if(mediaPlayer?.isPlaying as Boolean){
mediaPlayer?.pause()
currentSongHelperObject?.isPlaying = false
playPause?.setBackgroundResource(R.drawable.play_icon)
}else{
mediaPlayer?.start()
currentSongHelperObject?.isPlaying = true
playPause?.setBackgroundResource(R.drawable.pause_icon)
}
})
playNextButton?.setOnClickListener({
currentSongHelperObject?.isPlaying = true
if(currentSongHelperObject?.isShuffle as Boolean){
playNext("PlayShuffle")
}else{
playNext("playNextNormal")
}
})
playPreviousButton?.setOnClickListener({
currentSongHelperObject?.isPlaying = true
if (currentSongHelperObject?.isLoop as Boolean)
loopButton?.setBackgroundResource(R.drawable.loop_white_icon)
playPrevious()
})
}
fun playNext(check: String){
if(check.equals("playNextNormal",true)){
currentPosition = currentPosition + 1
}else if (check.equals("PlayShuffle",true)){
var randonObject = Random()
var randomPosition = randonObject.nextInt(fetchSongs?.size?.plus(1) as Int)
currentPosition = randomPosition
}
if(currentPosition == fetchSongs?.size){
currentPosition = 0
}
currentSongHelperObject?.isLoop = false
var nextSong = fetchSongs?.get(currentPosition)
currentSongHelperObject?.songTitle = nextSong?.songTittle
currentSongHelperObject?.songArtist = nextSong?.songArtist
currentSongHelperObject?.songPath = nextSong?.songData
currentSongHelperObject?.songId = nextSong?.songId as? Long
updateTextViews(currentSongHelperObject?.songTitle as String,currentSongHelperObject?.songArtist as String)
mediaPlayer?.reset()
try {
mediaPlayer?.setDataSource(myActivity,Uri.parse(currentSongHelperObject?.songPath))
mediaPlayer?.prepare()
mediaPlayer?.start()
processInformation(mediaPlayer as MediaPlayer)
}catch (e: Exception){
e.printStackTrace()
}
}
fun playPrevious(){
currentPosition = currentPosition - 1
if(currentPosition == -1)
currentPosition = 0
if (currentSongHelperObject?.isPlaying as Boolean)
playPauseButton?.setBackgroundResource(R.drawable.pause_icon)
else
playPauseButton?.setBackgroundResource(R.drawable.play_icon)
currentSongHelperObject?.isLoop = false
val nextSong = fetchSongs?.get(currentPosition)
currentSongHelperObject?.songTitle = nextSong?.songTittle
currentSongHelperObject?.songArtist = nextSong?.songArtist
currentSongHelperObject?.currentPosition = currentPosition
currentSongHelperObject?.songId = nextSong?.songId as Long
updateTextViews(currentSongHelperObject?.songTitle as String,currentSongHelperObject?.songArtist as String)
mediaPlayer?.reset()
try {
mediaPlayer?.setDataSource(activity,Uri.parse(currentSongHelperObject?.songPath))
mediaPlayer?.prepare()
mediaPlayer?.start()
processInformation(mediaPlayer as MediaPlayer)
}catch (e: Exception){
e.printStackTrace()
}
}
fun updateTextViews(songTitle: String,songArtist: String){
songTittle.setText(songTitle)
songArtistXYZ.setText(songArtist)
}
fun processInformation(mediaplayer: MediaPlayer){
val finalTimeXYZ = mediaplayer.duration
val startTimeXYZ = mediaplayer.currentPosition
startTime?.setText(String.format("%d:%d",
TimeUnit.MILLISECONDS.toMinutes(startTimeXYZ?.toLong() as Long),
TimeUnit.MILLISECONDS.toSeconds(startTimeXYZ?.toLong() as Long) -
TimeUnit.MILLISECONDS.toSeconds(TimeUnit.MILLISECONDS.toMinutes(startTimeXYZ?.toLong() as Long))))
endTime?.setText(String.format("%d:%d",
TimeUnit.MILLISECONDS.toMinutes(finalTimeXYZ?.toLong() as Long),
TimeUnit.MILLISECONDS.toSeconds(finalTimeXYZ?.toLong() as Long) -
TimeUnit.MILLISECONDS.toSeconds(TimeUnit.MILLISECONDS.toMinutes(finalTimeXYZ?.toLong() as Long))))
seekBar?.setProgress(startTimeXYZ)
Handler().postDelayed(updateSongTime,1000)
}
}
日志： -
11-10 02:10:27.941 2706-2721/com.vikanshu.echo E/libEGL: load_driver(/system/lib/egl/libGLES_emulation.so): dlopen failed: library "/system/lib/egl/libGLES_emulation.so" not found
11-10 02:10:28.127 2706-2721/com.vikanshu.echo E/EGL_emulation: tid 2721: eglSurfaceAttrib(1174): error 0x3009 (EGL_BAD_MATCH)
11-10 02:10:29.500 2706-2721/com.vikanshu.echo E/EGL_emulation: tid 2721: eglSurfaceAttrib(1174): error 0x3009 (EGL_BAD_MATCH)
11-10 02:10:40.882 2706-2706/com.vikanshu.echo E/MediaPlayer: start called in state 1, mPlayer(0x0)
11-10 02:10:40.883 2706-2706/com.vikanshu.echo E/MediaPlayer: error (-38, 0)
11-10 02:10:40.883 2706-2706/com.vikanshu.echo E/MediaPlayer: Attempt to call getDuration in wrong state: mPlayer=0x0, mCurrentState=0
11-10 02:10:40.912 2706-2706/com.vikanshu.echo E/MediaPlayer: Error (-38,0)
11-10 02:10:40.914 2706-2706/com.vikanshu.echo E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.vikanshu.echo, PID: 2706
kotlin.TypeCastException: null cannot be cast to non-null type kotlin.Long
at com.vikanshu.echo.Fragments.SongPlayingFragment.playNext(SongPlayingFragment.kt:235)
at com.vikanshu.echo.Fragments.SongPlayingFragment.onSongComplete(SongPlayingFragment.kt:160)
at com.vikanshu.echo.Fragments.SongPlayingFragment$onActivityCreated$1.onCompletion(SongPlayingFragment.kt:132)
at android.media.MediaPlayer$EventHandler.handleMessage(MediaPlayer.java:2943)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
答案 0 :(得分：0)
您收到此错误是因为您尝试将null投射到Long：
val x: Long? = null as Long
// >>> Exception in thread "main" kotlin.TypeCastException:
// >>> null cannot be cast to non-null type kotlin.Long
要修复它，您可以使用 safe cast operator ：
val x: Long? = null as? Long
println(x) // >>> null
但你最好弄明白为什么你得到null价值。