SongList Code in the image Not able to understand what actually the error is and why it is caused.Error shown shown below.
W/System.err: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
W/System.err: at android.os.Handler.<init>(Handler.java:200)
W/System.err: at android.os.Handler.<init>(Handler.java:114)
W/System.err: at android.app.Activity.<init>(Activity.java:754)
W/System.err: at android.app.ListActivity.<init>(ListActivity.java:175)
W/System.err: at com.example.vipul.finalproject.PlayListActivity.<init>(PlayListActivity.java:0)
W/System.err: at com.example.vipul.finalproject.SongList.scanSongs(SongList.java:296)
W/System.err: at com.example.vipul.finalproject.activities.ActivityMenuMain$ScanSongs.doInBackground(ActivityMenuMain.java:299)
W/System.err: at com.example.vipul.finalproject.activities.ActivityMenuMain$ScanSongs.doInBackground(ActivityMenuMain.java:289)
W/System.err: at android.os.AsyncTask$2.call(AsyncTask.java:295)
W/System.err: at java.util.concurrent.FutureTask.run(FutureTask.java:237)
W/System.err: at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
W/System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
W/System.err: at java.lang.Thread.run(Thread.java:818)
See this article to understand the whole Looper
/ Handler
relationship.
Long story short, your Thread#run()
method must follow a structure like so:
new Thread(new Runnable() {
@Override
public void run() {
Looper.prepare();
mHandler = new Handler();
Looper.loop();
}
}).start();
The best explanation on why you need a looper on one thread to save instructions and another thread to execute them. In a multi thread application task may come while executing other task.
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