java.lang.NullPointerException: Attempt to invoke virtual method 'int com.github.derlio.waveform.soundfile.SoundFile.getSampleRate()' on a null object reference

[charlieporth1]

@derlio

I get this error

 E/AndroidRuntime: FATAL EXCEPTION: main
                                                                           Process: com.studiosoapps.studioso, PID: 18253
                                                                           java.lang.NullPointerException: Attempt to invoke virtual method 'int com.github.derlio.waveform.soundfile.SoundFile.getSampleRate()' on a null object reference
                                                                               at com.github.derlio.waveform.SimpleWaveformView.setAudioFile(SimpleWaveformView.java:74)
                                                                               at com.studiosoapps.studioso.recordings.RecordedAudioListener$9$2.run(RecordedAudioListener.java:355)
                                                                               at android.os.Handler.handleCallback(Handler.java:751)
                                                                               at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                               at android.os.Looper.loop(Looper.java:154)
                                                                               at android.app.ActivityThread.main(ActivityThread.java:6776)
                                                                               at java.lang.reflect.Method.invoke(Native Method)
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)

this is my code

package com.studiosoapps.studioso.recordings;


import android.media.AudioManager;
import android.media.MediaPlayer;

import android.os.Environment;
import android.os.Handler;

import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.Toast;

import com.github.derlio.waveform.SimpleWaveformView;
import com.github.derlio.waveform.soundfile.SoundFile;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.storage.FileDownloadTask;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.StorageReference;
import com.studiosoapps.studioso.R;

import java.io.File;
import java.io.IOException;
import static com.crashlytics.android.Crashlytics.TAG;

public class RecordedAudioListener extends AppCompatActivity implements MediaPlayer.OnPreparedListener, SimpleWaveformView.WaveformListener {

//    public static ArrayList<Object> urlName = new ArrayList<>();
    public static String fileName;
    public static String urlName;
    public static String urlNameOrg;
    public static String urlNameNew;
    private SimpleWaveformView mWaveformView;



    private Button buttonPlayStop;
    private SeekBar seekBar;
//    private static final String TAG = "RecordedAudioListener";

    private MediaPlayer mediaPlayer;
    //path to the audio file
    private String mediaFile;



    FirebaseStorage storage = FirebaseStorage.getInstance();
    String UID = FirebaseAuth.getInstance().getUid();

    //https://www.sitepoint.com/a-step-by-step-guide-to-building-an-android-audio-player-app/
    private final Handler handler = new Handler();

    // Here i override onCreate method.
    //
    // setContentView() method set the layout that you will see then
    // the application will starts
    //
    // initViews() method i create to init views components.

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recorded_audio_listener);
//https://www.hrupin.com/2010/12/simple-android-mp3-media-player/comment-page-1
        urlNameOrg = RecordedAudioViewer.urlReturn();
        fileName = RecordedAudioViewer.nameReturn();
        Log.d(TAG, "onCreate: urlNameOrg " + urlNameOrg);
//        urlNameOrg = urlNameOrg.substring(0, urlNameOrg.indexOf("=") - 1);
        urlNameNew = urlNameOrg.replace("{DownloadURL=","");
        urlName = urlNameNew.replace("}","");

        Log.d(TAG, "onCreate: urlName " + urlName);
        Log.d(TAG, "onCreate: urlNameOrg new " + urlNameOrg);
        Log.d(TAG, "onCreate: fileName "+ fileName);

        StorageReference httpsReference = storage.getReferenceFromUrl(String.valueOf(urlName));
//        File localFile = null;
//        try {
//            localFile = File.createTempFile("videos", "mp4");
//        } catch (IOException e) {
//            e.printStackTrace();
//        }
        File directory = new File(Environment.getExternalStorageDirectory().getAbsolutePath(), "Studioso");
        File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath(), "Studioso" + "/" + fileName);

        Log.d(TAG, "createDir: Dir == " + directory);
        Log.d(TAG, "createDir: file dir == " + file);
        if (!directory.exists() || !directory.isDirectory()) {
            directory.mkdirs();
            Toast.makeText(RecordedAudioListener.this, "Media file not ready", Toast.LENGTH_SHORT).show();
            Log.d(TAG, "createDir: making directory");
//            if ( buttonPlayStop != null ) buttonPlayStop.setEnabled(false);

            httpsReference.getFile(directory).addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {
                @Override
                public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) {
                    // Local temp file has been created
                    Log.d(TAG, "createDir: Downloading files complete");
                }
            }).addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception exception) {
                    // Handle any errors
                    Log.d(TAG, "createDir: Downloading files failure");
                }
            });
        }
        else if (directory.exists() && !file.exists() ) {
//            if ( buttonPlayStop != null ) buttonPlayStop.setEnabled(false);
            Toast.makeText(RecordedAudioListener.this, "Media file not ready", Toast.LENGTH_SHORT).show();
            Log.d(TAG, "createDir: Downloading files");
            httpsReference.getFile(directory).addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {
                @Override
                public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) {
                    // Local temp file has been created
                    Log.d(TAG, "createDir: Downloading files complete");
                }
            }).addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception exception) {
                    // Handle any errors
                    Log.d(TAG, "createDir: Downloading files failure");
                }
            });



        }
        else {
            Log.d(TAG, "createDir: files are there");
            Toast.makeText(RecordedAudioListener.this, "Media file not ready", Toast.LENGTH_SHORT).show();
//            if ( buttonPlayStop != null ) buttonPlayStop.setEnabled(false);
        }

        mediaFile = directory + "/" + fileName;



        initViews();
        mWaveformView = (SimpleWaveformView) findViewById(R.id.waveform);
        mWaveformView.setWaveformListener(this);

    }


    // This method set the setOnClickListener and method for it (buttonClick())
    private void initViews() {

//        buttonPlayStop.setOnClickListener(new View.OnClickListener() {@Override public void onClick(View v) {buttonClick();}});

//       mediaPlayer = MediaPlayer.create(this,  Uri.parse(mediaFile));

        mediaPlayer = new MediaPlayer();
        mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
        try {
            mediaPlayer.setDataSource(mediaFile);
//            mediaPlayer.setDataSource(getApplication(),Uri.parse(mediaFile));
//                mediaPlayer.setOnPreparedListener(this);
            mediaPlayer.setOnPreparedListener(this);
            mediaPlayer.prepareAsync();
            Log.d(TAG, "initViews: mediaPlayer input file set  " + mediaFile);
        } catch (IOException e) {
            e.printStackTrace();
        }

//        seekBar.setMax(mediaPlayer.getDuration());
//        seekBar.setOnTouchListener(new View.OnTouchListener() {
//            @Override
//            public boolean onTouch(View v, MotionEvent event) {
//                seekChange(v);
//                return false;
//            }
//        });
    }
//
//    public void startPlayProgressUpdater() {
//
//        seekBar.setProgress(mediaPlayer.getCurrentPosition());
//            if (mediaPlayer.isPlaying()) {
//
//                Runnable notification = new Runnable() {
//                    public void run() {
//                        startPlayProgressUpdater();
//                    }
//                };
////                handler.postDelayed(notification, 1000);
//            } else {
//                if (mediaPlayer != null) {
//                    mediaPlayer.pause();
//                }
////                buttonPlayStop.setText("Play");
////                seekBar.setProgress(0);
//            }
//
//    }

    // This is event handler thumb moving event
    private void seekChange(View v){
        if(mediaPlayer.isPlaying()){
            SeekBar sb = (SeekBar)v;
            mediaPlayer.seekTo(sb.getProgress());
        }
    }

    // This is event handler for buttonClick event
    private void buttonClick(){
        if (buttonPlayStop.getText() == "Play") {
            buttonPlayStop.setText("Pause");
            try{
                mediaPlayer.start();
//                startPlayProgressUpdater();
                updateSeek();
                Log.d(TAG, "buttonClick: mediaPlayer Started sucessfully");
            }catch (IllegalStateException e) {
                mediaPlayer.pause();
                Log.d(TAG, "buttonClick: mediaPlayer failed IllegalStatus ");
            }
        }else {
            mediaPlayer.pause();
            buttonPlayStop.setText("Play");

        }
    }

            @Override
            public void onPrepared(MediaPlayer mp) {
                // Do something. For example: playButton.setEnabled(true);
//                buttonPlayStop.setEnabled(true);

                        buttonPlayStop = (Button) findViewById(R.id.ButtonPlayStop);
                        buttonPlayStop.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                buttonClick();
                            }
                        });
                        buttonPlayStop.setText("Play");

//                mediaPlayer.start();
                doTheWave();
                Toast.makeText(RecordedAudioListener.this, "Media file downloaded and ready to play", Toast.LENGTH_LONG).show();
                Log.d(TAG, "mediaPlayer: mediaPlayer ready");
                mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
                    @Override
                    public void onCompletion(MediaPlayer mediaPlayer) {
                        mediaPlayer.stop();
                        mediaPlayer.release();
                        mediaPlayer = null;
                    }
                });


                new Thread(new Runnable() {
                    public void run() {
                        seekBar = (SeekBar) findViewById(R.id.SeekBar01);
                        seekBar.setMax(mediaPlayer.getDuration());

                        seekBar.setOnTouchListener(new View.OnTouchListener() {
                            @Override
                            public boolean onTouch(View v, MotionEvent event) {
                                seekChange(v);
                                return false;
                            }
                        });
                    }
                }).start();

            }
    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mediaPlayer != null) {
            mediaPlayer.stop();
            mediaPlayer.release();
            mediaPlayer = null;
        }
    }

    private void updateSeek() {

        new Thread(new Runnable() {
            public void run() {
                Log.d(TAG, "updateSeek: while loop will run"); //note this isn't in loop because of performance
                while (mediaPlayer.isPlaying()) {

                    seekBar.setProgress(mediaPlayer.getCurrentPosition());
                    if (!mediaPlayer.isPlaying()) {
                        break;
                    }
                }
            }
        }).start();

    }

    @Override
    public void onWaveformDraw() {
        if (mediaPlayer.isPlaying()) {
            updateDisplay();
        }

    }

    private synchronized void updateDisplay() {
        if (mediaPlayer.isPlaying() && mediaPlayer != null) {
            int now = mediaPlayer.getCurrentPosition();
            mWaveformView.setPlaybackPosition(now);
        }
//
//        mWaveformView.setParameters(mStartPos, mEndPos, mOffset);
//        mWaveformView.invalidate();

    }
    private void doTheWave() {
        new Thread(new Runnable() {
            public void run() {
                try {
                    File dir = Environment.getExternalStorageDirectory();
                    final File withDir = new File(dir, "Studioso");
                    final File file = new File(withDir, fileName);

                    final SoundFile soundFile = SoundFile.create(file.getPath(), new SoundFile.ProgressListener() {

                        int lastProgress = 0;


                        @Override
                        public boolean reportProgress(double fractionComplete) {
                            final int progress = (int) (fractionComplete * 100);
                            if (lastProgress == progress) {
                                return true;
                            }
                            lastProgress = progress;
                            Log.i(TAG, "LOAD FILE PROGRESS:" + progress);

                            return true;
                        }
                    });

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            DisplayMetrics metrics = new DisplayMetrics();
                            getWindowManager().getDefaultDisplay().getMetrics(metrics);

                            mWaveformView.setAudioFile(soundFile);

//                            mWaveformView.invalidate();
                        }
                    });

                } catch (IOException e) {
                    e.printStackTrace();
                } catch (SoundFile.InvalidInputException e) {
                    e.printStackTrace();
                }

            }
        }).start();
    }
}

any advice I don't know why this error is happening?