I can not understand how to free up the memory from MediaPlayer when you click onBackpressed if the player plays

import java.io.file;
Import java.io.fileoutputstream;
Import java.io.ioException;
Import java.io.inputstream;
Import java.net.httpurlConnection;
Import java.net.malformedurlexception;
Import java.net.url;
Import Android.app.ActiveIVITY;
Import android.app.progressDialog;
Import android.content.context;
Import Android.Content.intent;
Import Android.media.AudioManager;
Import Android.media.mediaPlayer;
Import Android.os.asynctask;
Import android.os.Bundle;
Import android.os.Environment;
Import Android.os.Handler;
Import android.util.Base64;
Import Android.View.View;
Import android.view.view.onclicklistener;
Import android.widget.button;
Import android.widget.seekbar;
Import android.widget.textView;
Import android.media.mediaplayer.onbufferingUpdatelistener;
Import android.media.mediaplayer.oncompletionlistener;
Import android.view.motionEvent;
Import android.view.view.ontouchlistener;
Public Class SingleMenuiteMactivity Extends Activity Implements OnClicklistener, Ontouchlistener, OnCompletionListener, OnBufferingUpdatelistener {
  Private Button BTN_PLAY, BTN_PAUSE, BTN_STOP;
  Private Seekbar Seekbar;
  Private MediaPlayer MediaPlayer;
  Private INT Lengthofaudio;
  Private Final Handler Handler = New Handler ();
  // XML Node Keys
  Static Final String Login = "Login";
  STATIC FINAL STRING PASS = "PASS";
  Static Final String Key_Date = "Date";
  STATIC FINAL STRING KEY_FROM = "FROM_";
  Static Final String Key_To = "To_";
  STATIC FINAL STRING KEY_DURATION = "DURATION";
  // Static Final String Key_Typemsg = "TypeSG";
  STATIC FINAL STRING KEY_FILENAME = "FILENAME";
  Private Final String Path = Environment .GetExternalStoragedirectory () + "/ Android / Data / IDEV.Sedek.ekeyMangorecords / cache /";
  String Filename, Data, ErrorCode;
  INT DATA1;
  int downloaddsize = 0;
  int TotalSize = 0;
  int kilobytes = 0;
  Private progressdialog PD;
  Private Final RunnaBle R = New Runnable () {
    @Override
    Public void Run () {
      Updateseekprogress ();
    }
  };
  @Override
  Public Void OnCreate (Bundle SavedInstanceState) {
    Super.ONCREATE (SavedInstanceState);
    setContentView (R.Layout.Single_List_Item);
    init ();
  }
  Private void init () {
    BTN_PLAY = (Button) FindViewByid (R.ID.BTN_PLAY);
    BTN_PLAY.SetonClicklistener (this);
    BTN_PAUSE = (Button) FindViewByid (R.ID.BTN_PAUSE);
    BTN_PAUSE.SetonClicklistener (this);
    btn_pause.setenabled (false);
    BTN_STOP = (Button) FindViewByID (R.ID.BTN_STOP);
    btn_stop.setonclicklistener (this);
    btn_stop.setenabled (false);
    Seekbar = (Seekbar) FindViewByid (R.ID.Seekbar1);
    Seekbar.setontouchlistener (this);
    MediaPlayer = New MediaPlayer ();
    MediaPlayer.SetonBufferingUpdatelistener (this);
    MediaPlayer.SetonCompletionListener (this);
    MediaPlayer.SetaudiostreamType (audioManager.stream_Music);
    // Getting Intent Data
    INTENT IN = GetIntent ();
    // Get Xml Values ​​From Previous Intent
    String Date = IN.GetStringExtra (key_date);
    String from_ = in.getStringextra (Key_From);
    STRING TO_ = IN.GETSTRINGEXTRA (KEY_TO);
    String Duration = IN.GetStringextra (key_duration);
    // String Typemsg = in.getStringextra (Key_typemsg);
    Final String FileName = IN.GetStringExtra (Key_FileName);
    // Displaying All Values ​​on the Screen
    TextView LBLDATE = (TextView) FindViewByid (R.ID.Date_Label);
    TextView LBLFrom_ = (textView) FindViewByID (R.ID.From__Label);
    TextView LBLTO_ = (textView) FindViewByid (R.ID.TO__Label);
    TextView LBLDURATION = (TextView) FindViewByID (R.ID.DURATION_LABEL);
    // TextView LBLTYPEMSG = (textView) FindViewByid (R.ID.Typemsg_Label);
    TextView LBLFILENAME = (textView) FindViewByid (R.ID.FileName_Label);
    lbldate.settext (date); 
lblfrom_.settext (from_);
    lblto_.settext (to_);
    LBLDURATION.SETTEXT (DURATION);
    //lbltypemsg.settext (typemsg);
    lblfilename.settext (FileName);
    Asynctask & lt; void, void, void & gt; ast = new asynctask & lt; void, void, void & gt; () {
      @Override
      PROTECTED VOID ONPREEXECUTE () {
        // TODO AUTO-GENERATED METHOD STUB
        pd = new progressdialog (singlemenuitemactivity.this);
        PD.Settitle ("File Loading");
        PD.SetMessage ("wait ...");
        PD.SetProgressStyle (progressdialog.style_horizontal);
        pd.show ();
      }
      @Override
      PROTECTED VOID DOINBACKGROUND (Void ... Params) {
        // TODO AUTO-GENERATED METHOD STUB
        getfile ();
        RETURN NULL;
      }
      @Override
      PROTECTED VOID ONPOSTEXECUTE (Void Result) {
        // TODO AUTO-GENERATED METHOD STUB
        pd.dismiss ();
        Try {
          INTENT IN = GetIntent ();
          String FileName = in.getStringExtra (Key_FileName);
          MediaPlayer.SetDataSource (Path + FileName);
          mediaplayer.prepare ();
          Lengthofaudio = mediaplayer.getduration ();
        } Catch (Exception E) {
        }
      }
    };
    ast.execute ();
  }
  Public Void GetFile () {
    INTENT IN = GetIntent ();
    String FileName = in.getStringExtra (Key_FileName);
    String login1 = in.getStringextra (Login);
    String Pass1 = In.GetStringextra (PASS);
    Try {
      String audio_path = "http://92.75.25.212:8080/imap/attachments/"+FileName;
      Audio_path = audio_path.replaceall ("", "% 20");
      String Username = login1;
      String Password = pass1;
      String UserPassword = UserName + ":" + Password;
      URL URL = NEW URL (Audio_Path);
      HttpurlConnection C = (httpurlconnection) url.openconnection ();
      C.SetRequestmethod ("Get");
      C.Setdooutput (TRUE);
      String Encoded = New String (Base64.Encode (UserPassword.getBytes (), Base64.no_Close));
      C.SetRequestProperty ("Authorization", "Basic" + Encoded);
      C.Connect ();
      File File = New File (Path);
      file.mkdirs ();
      String FileName = FileName;
      File OutputFile = New File (File, FileName);
      FileOutputStream FOS = New FileoutPutStream (OutputFile);
      Inputstream is = c.getInputStream ();
      TOTALSIZE = C.GetContentLength ();
      kilobytes = totalsize / 1024;
      Runonuithread (New Runnable () {
        Public void Run () {
          PD.Setmax (kilobytes);
          TextView FileSizeView = (textView) FindViewByid (R.ID.FileSizeView);
          filesizeview.settext (string.valueof (kilobytes));
        }
      });
      BYTE [] Buffer = New Byte [1024];
      int bufferlength = 0;
      while ((bufferlength = is.read (buffer)! = -1) {
        FOS.WRITE (Buffer, 0, BufferLength);
        downloadedsize + = bufferlength;
        Final int downloaddsize1 = downloadedsize / 1024; // kilobytes.
        // Update The ProgressBar //
        Runonuithread (New Runnable () {
          Public void Run () {
            pd.setprogress (downloadedsize1);
            Float Per = ((Float) downloadedsize1 / kilobytes) * 100;
            PD.SetMessage ("Download" + downloadedSize1 + "Kb from" + kilobytes + "kb (" + (int) per + "%)");
          }
        });
      }
      FOS.Close ();
      is.close ();
    } Catch (MalForMedurlexception E) {
      E.PrintStackTrace ();
    } Catch (IoException E) {
      E.PrintStackTrace ();
    }
  }
  @Override
  Public Void OnBufferingUpdate (Mediaplayer MediaPlayer, Int Percent) {
    Seekbar.setSecondaryProgress (Percent);
  }
  @Override 
Public Void OnCompletion (MediaPlayer MP) {
    BTN_PLAY.setenabled (TRUE);
    btn_pause.setenabled (false);
    btn_stop.setenabled (false);
  }
  @Override
  Public Boolean OnTouch (View V, MotionEvent Event) {
    if (MediaPlayer.Isplaying ()) {
      Seekbar TMPSEEKBAR = (Seekbar) V;
      MediaPlayer.Seekto ((Lengthofaudio / 100) * TMPSEEKBAR.getProgress ());
    }
    RETURN FALSE;
  }
  @Override
  Public Void OnClick (View View) {
    Switch (view.getid ()) {
    Case R.ID.BTN_Play:
      Playaudio ();
      Break;
    Case R.ID.BTN_PAUSE:
      pauseaudio ();
      Break;
    Case R.ID.BTN_STOP:
      stopaudio ();
      Break;
    Default:
      Break;
    }
    Updateseekprogress ();
  }
  Private Void UpdateSeekProgress () {
    if (MediaPlayer.Isplaying ()) {
      seekbar.setprogress ((int) (((Float) mediaplayer.getcurrentposition () / lengthofaudio) * 100));
      Handler.postdelayed (R, 1000);
    }
  }
  Private void Stopaudio () {
    // mediaplayer.stop ();
    Try {
      INTENT IN = GetIntent ();
      String FileName = in.getStringExtra (Key_FileName);
      mediaplayer.stop ();
      mediaplayer.reset ();
      MediaPlayer.SetDataSource (Path + FileName);
      mediaplayer.prepareAsync ();
    } Catch (Exception E) {
      E.PrintStackTrace ();
    }
    BTN_PLAY.setenabled (TRUE);
    btn_pause.setenabled (false);
    btn_stop.setenabled (false);
    seekbar.setprogress (0);
  }
  Private Void Pauseaudio () {
    mediaplayer.pause ();
    BTN_PLAY.setenabled (TRUE);
    btn_pause.setenabled (false);
  }
  Private void Playaudio () {
    mediaplayer.start ();
    BTN_PLAY.setenabled (false);
    btn_pause.setenabled (true);
    btn_stop.setenabled (true);
  }
  @Override
  Public void onbackpressed () {
    mediaplayer.stop ();
    mediaplayer.reset ();
    mediaplayer.release ();
    super.onbackpressed (); // gives an error
  }
}

Stektrays Exceptions:

11-11 12: 25: 11.209: w / dalvikvm (13875): threadid = 1: thread exiting with undcaught exception ( group = 0x41a52700)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): Fatal Exception: Main
11-11 12: 25: 11.209: E / AndroidRuntime (13875): java.lang.illegalstateException
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at Android.media.mediaPlayer.Isplaying (Native Method)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at idev.sedek.ekeymanngorecords.singlemenuitemactivity.updateseekprogress (singlemenuitemactivity.java:247)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at idev.sedek.ekeymanngorecords.seklemenuitemactivity.access $ 0 (singlemenuitemactivity.java:24)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at IDEV.Sedek.ekeyMangorecords.SingleMenuITEMActivity $ 1.run (SingleMenuItemActivity.java:7)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at Android.os.Handler.HandleCallback (Handler.java:730)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at Android.os.Handler.DispatchMessage (Handler.java:92)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at Android.os.looper.loop (Looper.java:137)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at Android.app.ActivityThread.Main (ActivityThread.java:103)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at java.lang.reflect.method.invokenative (Native Method)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at java.lang.reflect.method.invoke (Method.java:25)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at com.android.Internal.os.zygoteinit $ Methodargscaller.run (zygoteinit.java:737)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at com.android.internal.os.zygoteinit.main (zygoteinit.java:53)
11-11 12: 25: 11.209: E / AndroidRuntime (13875): at dalvik.system.nativeTart.main (Native Method)

Answer 1, Authority 100%

Why did you decide that the exception occurs in the row you marked? Judging by Stacktreys, it occurs on a 247 line in the updateseekprogress () method, which is most likely a string with the condition if (mediaplayer.isplaying ()) ... .

and the reason for this simple – updateseekprogress () continues to be called after mediaplayer.release (); in onbackpressed () .

And how does Documentation on MediaPlayer.Isplaying ( ) :

Throws IllegalstateException If The Internal Player Engine Has Not Been Initialized or Has Been Released .