เขียนโค้ด Record Audio ใน android studio แล้วแอพเด้งค่ะ code ไม่มี error ใดๆ

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.ro_cot_ta.audiotest">

    <uses-permission android:name="android.permission.RECORD_AUDIO" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

import android.media.MediaRecorder;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import java.io.IOException;

 public class MainActivity extends AppCompatActivity {
    private Button recstop;
    private TextView mRecordLabel;
    private static  final String LOG_TAG = "Record_Log";
    private MediaRecorder mRecorder;
    private String mFileName = null;

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

        recstop = (Button) findViewById(R.id.recstop);
        mRecordLabel = (TextView) findViewById(R.id.mRecordLabel);

        mFileName = getExternalCacheDir().getAbsolutePath();
        mFileName += "/rec_audio.3gp";

        recstop.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                if(motionEvent.getAction() == motionEvent.ACTION_DOWN) {

                    mRecordLabel.setText("Record start...");
                    startRecording();

                } else if (motionEvent.getAction() == MotionEvent.ACTION_UP){

                    mRecordLabel.setText("Record stop!!...");

                    stopRecording();
                }
                return false;

            }
        });

    }

     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;
     }


}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="com.example.ro_cot_ta.audiotest.MainActivity"
    android:gravity="center">

    <Button
        android:id="@+id/recstop"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="rec and stop"/>
    <TextView
        android:id="@+id/mRecordLabel"
        android:layout_marginTop="16dp"
        android:textSize="16dp"
        android:layout_below="@+id/recstop"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Tap and hold butt to reccord and stop"
        android:textAlignment="center"
        />


</RelativeLayout>