Ошибка надувания класса android.view.InflateException, не удалось найти класс java.lang.ClassNotFoundException

Когда я пытаюсь запустить приложение, я получаю исключение, которое отображается в заголовке.

Это мой XML-файл:

<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
    xmlns:app = "http://schemas.android.com/apk/res-auto"
    xmlns:tools = "http://schemas.android.com/tools"
    android:layout_width = "match_parent"
    android:layout_height = "match_parent"
    tools:context = ".MainActivity">


    <LinearLayout
        android:layout_width = "match_parent"
        android:layout_height = "wrap_content">

        <com.example.ruben.fileapp.MainActivity.PlayButton
            android:id = "@+id/play_button"
            android:layout_width = "wrap_content"
            android:layout_height = "wrap_content" />

        <com.example.ruben.fileapp.MainActivity.RecordButton
            android:id = "@+id/record_button"
            android:layout_width = "wrap_content"
            android:layout_height = "wrap_content" />

    </LinearLayout>

</LinearLayout>

Это мой MainActivity.java:

package com.example.ruben.fileapp;

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.media.MediaPlayer;
import android.media.MediaRecorder;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.AppCompatButton;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {


    private static final String LOG_TAG = "AudioRecordTest";
    private static final int REQUEST_RECORD_AUDIO_PERMISSION = 200;
    private static String mFileName = null;

    private RecordButton mRecordButton = null;
    private MediaRecorder mRecorder = null;

    private PlayButton   mPlayButton = null;
    private MediaPlayer mPlayer = null;

    // Requesting permission to RECORD_AUDIO
    private boolean permissionToRecordAccepted = false;
    private String [] permissions = {Manifest.permission.RECORD_AUDIO};



    //region permissionMethod
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode){
            case REQUEST_RECORD_AUDIO_PERMISSION:
                permissionToRecordAccepted  = grantResults[0] == PackageManager.PERMISSION_GRANTED;
                break;
        }

    if (!permissionToRecordAccepted ) finish();

}
//endregion

private void onRecord(boolean start) {
    if (start) {
        startRecording();
    } else {
        stopRecording();
    }
}

private void onPlay(boolean start) {
    if (start) {
        startPlaying();
    } else {
        stopPlaying();
    }
}

private void startPlaying() {
    mPlayer = new MediaPlayer();
    try {
        mPlayer.setDataSource(mFileName);
        mPlayer.prepare();
        mPlayer.start();
    } catch (IOException e) {
        Log.e(LOG_TAG, "prepare() failed");
    }
}

private void stopPlaying() {
    mPlayer.release();
    mPlayer = null;
}

private void startRecording() {
    mRecorder = new MediaRecorder();
    mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
    mRecorder.setOutputFile(mFileName);
    mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

    try {
        mRecorder.prepare();
    } catch (IOException e) {
        Log.e(LOG_TAG, "prepare() failed");
    }

    mRecorder.start();
}

private void stopRecording() {
    mRecorder.stop();
    mRecorder.release();
    mRecorder = null;
}
//region RecordButton
public class RecordButton extends AppCompatButton {
    boolean mStartRecording = true;

    OnClickListener clicker = new OnClickListener() {
        public void onClick( View v) {
            onRecord(mStartRecording);
            if (mStartRecording) {
                setText("Stop recording");
            } else {
                setText("Start recording");
            }
            mStartRecording = !mStartRecording;
        }
    };

    public RecordButton(Context ctx) {
        super(ctx);
        setText("Start recording");
        setOnClickListener(clicker);
    }
}
//endregion

//region PlayButton
public class PlayButton extends AppCompatButton {
    boolean mStartPlaying = true;

    OnClickListener clicker = new OnClickListener() {
        public void onClick(View v) {
            onPlay(mStartPlaying);
            if (mStartPlaying) {
                setText("Stop playing");
            } else {
                setText("Start playing");
            }
            mStartPlaying = !mStartPlaying;
        }
    };

    public PlayButton(Context ctx) {
        super(ctx);
        setText("Start playing");
        setOnClickListener(clicker);
    }
}
//endregion

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    // Record to the external cache directory for visibility
    mFileName = getExternalCacheDir().getAbsolutePath();
    mFileName += "/audiorecordtest.3gp";

    ActivityCompat.requestPermissions(this, permissions, REQUEST_RECORD_AUDIO_PERMISSION);

    LinearLayout ll = new LinearLayout(this);

    mRecordButton = (RecordButton) findViewById(R.id.record_button);

    mPlayButton = (PlayButton) findViewById(R.id.play_button);
    /*ll.addView(mRecordButton,
            new LinearLayout.LayoutParams(
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    0));*/
    //mPlayButton = new PlayButton(this);

    /*ll.addView(mPlayButton,
            new LinearLayout.LayoutParams(
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    0));
    setContentView(ll);*/


}

@Override
public void onStop() {
    super.onStop();
    if (mRecorder != null) {
        mRecorder.release();
        mRecorder = null;
    }

    if (mPlayer != null) {
        mPlayer.release();
        mPlayer = null;
    }
}

}

Это мой полный лог:

09-04 12:36:45.898 6198-6198/? I/art: Late-enabling -Xcheck:jni
    Reinit property: dalvik.vm.checkjni= false
09-04 12:36:46.143 6198-6198/com.example.ruben.fileapp W/System: ClassLoader referenced unknown path: /data/app/com.example.ruben.fileapp-1/lib/arm64
09-04 12:36:46.156 6198-6198/com.example.ruben.fileapp I/InstantRun: starting instant run server: is main process
09-04 12:36:46.185 6198-6198/com.example.ruben.fileapp I/HwCust: Constructor found for class android.app.HwCustActivityImpl
09-04 12:36:46.210 6198-6198/com.example.ruben.fileapp I/HwCust: Constructor found for class android.app.HwCustHwWallpaperManagerImpl
09-04 12:36:46.235 6198-6198/com.example.ruben.fileapp W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
09-04 12:36:46.318 6198-6198/com.example.ruben.fileapp E/HW-JPEG-DEC: [HME_JPEG_DEC_Delete](3321): HME_JPEG_DEC_Delete: decoder_ctx=null
09-04 12:36:46.344 6198-6198/com.example.ruben.fileapp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.ruben.fileapp, PID: 6198
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ruben.fileapp/com.example.ruben.fileapp.MainActivity}: android.view.InflateException: Binary XML file line #14: Binary XML file line #14: Error inflating class com.example.ruben.fileapp.MainActivity.PlayButton
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2793)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2864)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1567)
        at android.os.Handler.dispatchMessage(Handler.java:105)
        at android.os.Looper.loop(Looper.java:156)
        at android.app.ActivityThread.main(ActivityThread.java:6523)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:831)
     Caused by: android.view.InflateException: Binary XML file line #14: Binary XML file line #14: Error inflating class com.example.ruben.fileapp.MainActivity.PlayButton
     Caused by: android.view.InflateException: Binary XML file line #14: Error inflating class com.example.ruben.fileapp.MainActivity.PlayButton
     Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.ruben.fileapp.MainActivity.PlayButton" on path: DexPathList[[zip file "/data/app/com.example.ruben.fileapp-1/base.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_dependencies_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_0_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_1_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_2_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_3_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_4_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_5_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_6_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_7_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_8_apk.apk", zip file "/data/app/com.example.ruben.fileapp-1/split_lib_slice_9_apk.apk"],nativeLibraryDirectories=[/data/app/com.example.ruben.fileapp-1/lib/arm64, /system/lib64, /vendor/lib64, /system/vendor/lib64, /product/lib64]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:380)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
        at android.view.LayoutInflater.createView(LayoutInflater.java:616)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:798)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:738)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:869)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:832)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:872)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:832)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:377)
        at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287)
        at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139)
        at com.example.ruben.fileapp.MainActivity.onCreate(MainActivity.java:158)
        at android.app.Activity.performCreate(Activity.java:6910)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2746)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2864)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1567)
        at android.os.Handler.dispatchMessage(Handler.java:105)
        at android.os.Looper.loop(Looper.java:156)
        at android.app.ActivityThread.main(ActivityThread.java:6523)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:831)
09-04 12:36:46.353 6198-6198/com.example.ruben.fileapp I/Process: Sending signal. PID: 6198 SIG: 9

Буду признателен за любую помощь.

Спасибо

P.S .: Это мой первый вопрос, размещенный на stackoverflow, если что-то не так, как я спрашиваю, не стесняйтесь сказать мне.