MediaPlayer: MediasetNextMediaPlayer() not working before Android 5 api 21

I want to run this code on pre Lollipop devices , but it is not working because of MediasetNextMediaPlayer()

I have test the code on the 21+ API and working as required.

There are 3 mediaPlayers with OnCompletionListener

 public void playall(final View view) {
        x = 0;
        i = 0;
        j = 0;
        i = i + Sound_id;
        int en_sound = getResources().getIdentifier("e" + i, "raw", getPackageName());
        mpe = MediaPlayer.create(list_activity.this, en_sound);
        mpe.start();

        mpe.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
                                        @Override
                                        public void onCompletion(MediaPlayer mediaPlayer) {
                                            int ar_sound = getResources().getIdentifier("a" + i, "raw", getPackageName());
                                            mpa = MediaPlayer.create(list_activity.this, ar_sound);
                                            mpa.start();
                                            try {
                                                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                                                    mpa.setNextMediaPlayer(mpe);
                                                } else {
                                                    Toast.makeText(list_activity.this, "Error", Toast.LENGTH_SHORT).show();
                                                }

                                            } catch (RuntimeException e) {
                                                Log.d(TAG, "Error");
                                            }

                                            mpe.setVolume(0, 0);
                                            if (j < (adapterWrapper.getAdapter().getCount())) {
                                                if (x <= 0) {
                                                    i = i + 1;
                                                    j = j + 1;
                                                }
                                                x = x - 1;

                                            }
                                            mpa.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
                                                                            @Override
                                                                            public void onCompletion(MediaPlayer mediaPlayer) {

                                                                                int en_sound2 = getResources().getIdentifier("e" + i, "raw", getPackageName());
                                                                                mpt = MediaPlayer.create(list_activity.this, en_sound2);
                                                                                mpt.start();
                                                                                if (j < (adapterWrapper.getAdapter().getCount())) {
                                                                                    try {
                                                                                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                                                                                            mpt.setNextMediaPlayer(mpa);
                                                                                        } else {
                                                                                            Toast.makeText(list_activity.this, "Error", Toast.LENGTH_SHORT).show();
                                                                                        }

                                                                                    } catch (RuntimeException e) {
                                                                                        Log.d(TAG, "Error");
                                                                                    }

                                                                                } else {
                                                                                    stop(view);
                                                                                }

                                                                            }
                                                                        }

                                            );
                                        }

                                    }

        );

}

Logcat

04-27 16:03:27.210 128-9135/? A/libc: @@@ ABORTING: heap corruption detected by dlmalloc
04-27 16:03:27.210 128-9135/? A/libc: Fatal signal 11 (SIGSEGV) at 0xdeadbaad (code=1), thread 9135 (TimedEventQueue)
04-27 16:03:27.730 8882-8894/learnenglish.listenenglish.englisheasy E/MediaPlayer: error (100, 0)
04-27 16:03:27.730 8882-8894/learnenglish.listenenglish.englisheasy E/MediaPlayer: error (100, 0)
04-27 16:03:27.730 120-120/? E/local_camera: We have a problem with the hw connection 0 (Success)
04-27 16:03:27.730 121-121/? E/local_camera: We have a problem with the hw connection 0 (Success)
04-27 16:03:27.734 8882-8882/learnenglish.listenenglish.englisheasy E/MediaPlayer: Error (100,0)
04-27 16:03:27.810 9172-9172/? E/MonoPipe: Failed to fetch local time frequency when constructing a MonoPipe (res = -32).  getNextWriteTimestamp calls will be non-functional
04-27 16:03:28.738 9172-9172/? E/WVMExtractor: Failed to open libwvm.so
04-27 16:03:28.742 9172-9172/? A/libc: Fatal signal 11 (SIGSEGV) at 0x00000007 (code=1), thread 9172 (mediaserver)
04-27 16:03:28.922 123-123/? E/Corkscrew: unrecognized DW_CFA_* instruction: 0x10
04-27 16:03:28.962 8882-8882/learnenglish.listenenglish.englisheasy E/MediaPlayer: Error (100,0)
04-27 16:03:28.962 8882-8882/learnenglish.listenenglish.englisheasy E/MediaPlayer: Unable to to create media player
04-27 16:03:28.966 8882-8894/learnenglish.listenenglish.englisheasy E/MediaPlayer: error (100, 0)
04-27 16:03:28.966 8882-8894/learnenglish.listenenglish.englisheasy E/MediaPlayer: error (100, 0)
04-27 16:03:28.966 8882-8894/learnenglish.listenenglish.englisheasy E/MediaPlayer: error (100, 0)
04-27 16:03:28.966 8882-8894/learnenglish.listenenglish.englisheasy E/MediaPlayer: error (100, 0)
04-27 16:03:28.966 8882-8882/learnenglish.listenenglish.englisheasy E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                      java.lang.NullPointerException
                                                                                          at learnenglish.listenenglish.englisheasy.list_activity$2.onCompletion(list_activity.java:513)
                                                                                          at android.media.MediaPlayer$EventHandler.handleMessage(MediaPlayer.java:2046)
                                                                                          at android.os.Handler.dispatchMessage(Handler.java:99)
                                                                                          at android.os.Looper.loop(Looper.java:137)
                                                                                          at android.app.ActivityThread.main(ActivityThread.java:5103)
                                                                                          at java.lang.reflect.Method.invokeNative(Native Method)
                                                                                          at java.lang.reflect.Method.invoke(Method.java:525)
                                                                                          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
                                                                                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
                                                                                          at dalvik.system.NativeStart.main(Native Method)
04-27 16:03:29.234 1333-1398/system_process E/AudioService: Media server died.
04-27 16:03:32.998 9268-9268/? E/MonoPipe: Failed to fetch local time frequency when constructing a MonoPipe (res = -32).  getNextWriteTimestamp calls will be non-functional
04-27 16:03:33.238 1333-1398/system_process E/AudioService: Media server started.
04-27 16:03:33.738 9174-9174/? E/local_camera: We have a problem with the hw connection 0 (Success)
04-27 16:03:33.738 9173-9173/? E/local_camera: We have a problem with the hw connection 0 (Success)

                                               [ 04-27 16:03:34.654    58:   58 D/         ]
                                               Socket deconnection

                                               [ 04-27 16:03:36.666    58:   58 D/         ]
                                               Socket deconnection

                                               [ 04-27 16:03:38.682    58:   58 D/         ]
                                               Socket deconnection