android异步任务,Android：运行4个异步任务（适用于Rest API），在完成所有任务后等待并启动另一个活动[重复]...
这个问题在这里已有答案：
我有异步任务的问题 . 我试图运行4个异步任务，从last.fm rest api获取数据 .
My task points:
异步或并行运行4个任务(计数无关紧要，但必须大于1)
从last.fm rest api中获取数据(用于从last.fm api获取数据使用de.umass.lastfm java库)
等待完成所有任务
使用提取的数据启动另一个活动
调用异步任务的函数：
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_animation)
initViewElements();
mArtistName = intent.getStringExtra("ARTIST_NAME");
Log.i(TAG, mArtistName);
setAnimationData();
getArtistData(mArtistName);
startActivity(Intent(this, DetailsActivity::class.java))
}
功能在哪里介绍我的任务
private fun getArtistData(name: String) {
val getArtistDataAsync = object : AsyncTask() {
override fun doInBackground(vararg args: String?): Artist? {
return Artist.getInfo(args[0], "26cc2ebf6da38bc646733f661bfc6268");
}
override fun onPostExecute(result: Artist?) {
super.onPostExecute(result)
CommonUtilities.artistInstance = result as Artist;
}
}
val getTopTracksAsync = object : AsyncTask>(){
override fun doInBackground(vararg args: String?): ArrayList? {
return Artist.getTopTracks(args[0], "26cc2ebf6da38bc646733f661bfc6268") as ArrayList;
}
override fun onPostExecute(result: ArrayList?) {
super.onPostExecute(result)
CommonUtilities.trackListInstance = result;
}
}
val getSimilarBandsAsync = object : AsyncTask>(){
override fun doInBackground(vararg args: String?): ArrayList? {
return Artist.getSimilar(args[0], "26cc2ebf6da38bc646733f661bfc6268") as ArrayList?
}
override fun onPostExecute(result: ArrayList?) {
super.onPostExecute(result)
CommonUtilities.artistListInstance = result; //Instance Messenger Pattern
}
}
val getTopAlbumsAsync = object : AsyncTask>(){
override fun doInBackground(vararg p0: String?): ArrayList? {
return Artist.getTopAlbums(p0[0],"26cc2ebf6da38bc646733f661bfc6268") as ArrayList?;
}
override fun onPostExecute(result: ArrayList?) {
super.onPostExecute(result)
CommonUtilities.albumListInstance = result; //Instance Messenger Pattern
}
}
getArtistDataAsync.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, name)
getSimilarBandsAsync.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, name)
getTopTracksAsync.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, name)
getTopAlbumsAsync.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, name)
}
堆栈跟踪：
E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #4
Process: pw.osin.musicexpert, PID: 17334
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:841)
Caused by: de.umass.lastfm.CallException: Caching/Reloading failed
at de.umass.lastfm.Caller.call(Caller.java:246)
at de.umass.lastfm.Caller.call(Caller.java:189)
at de.umass.lastfm.Caller.call(Caller.java:185)
at de.umass.lastfm.Artist.getSimilar(Artist.java:144)
at de.umass.lastfm.Artist.getSimilar(Artist.java:132)
at pw.osin.musicexpert.activities.AnimationActivity$getArtistData$getSimilarBandsAsync$1.doInBackground(AnimationActivity.kt:120)
at pw.osin.musicexpert.activities.AnimationActivity$getArtistData$getSimilarBandsAsync$1.doInBackground(AnimationActivity.kt:117)
at android.os.AsyncTask$2.call(AsyncTask.java)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:841)
02-17 05:49:05.636 17334-17432/pw.osin.musicexpert W/dalvikvm: threadid=13: thread exiting with uncaught exception (group=0x4179ed58)
那我怎么能解决这个错误呢？
等待任务如何完成？
哪里需要调用startActivity方法？
我使用的是Kotlin，但任务方法与java类似 . 如果你能告诉我如何使用java编写我的代码也会很棒 .
谢谢