java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() Error

Issue

SongList Code in the imageNot 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)

Solution

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.

Answered By - Pomagranite