This code is written to record a file and return a sequence of the values from the audio file so that I can do some signal processing. I keep getting a null pointer exception on this line towards the bottom:
dos.write(buffer, 0, bufferSize);
Can someone explain what is wrong and what I should change?
package com.example.wesle.noisemachine;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.media.MediaPlayer;
import android.media.MediaRecorder;
import android.os.Environment;
import android.widget.Toast;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
public class ReceiveScreen extends AppCompatActivity {
private Button buttonStart, buttonStop, buttonPlay, buttonDecode;
private MediaRecorder mediaRecorder = new MediaRecorder();
private String outputFile;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_receive_screen);
buttonStart = (Button) findViewById(R.id.buttonStart);
buttonStop = (Button) findViewById(R.id.buttonStop);
buttonPlay = (Button) findViewById(R.id.buttonPlay);
buttonDecode = (Button) findViewById(R.id.buttonDecode);
buttonStop.setEnabled(false);
buttonPlay.setEnabled(false);
outputFile = Environment.getExternalStorageDirectory().getAbsolutePath() + "/recording.3gp";
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
mediaRecorder.setOutputFile(outputFile);
buttonStart.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
try {
mediaRecorder.prepare();
mediaRecorder.start();
} catch (IllegalStateException ise) {
System.out.println("ISE Catch");
} catch (IOException ioe) {
System.out.println("IO Catch");
}
buttonStart.setEnabled(false);
buttonStop.setEnabled(true);
Toast.makeText(getApplicationContext(), "Recording started", Toast.LENGTH_LONG).show();
}
});
buttonStop.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
mediaRecorder.stop();
mediaRecorder.release();
buttonStop.setEnabled(false);
buttonPlay.setEnabled(true);
buttonStart.setEnabled(true);
Toast.makeText(getApplicationContext(), "Recording Completed", Toast.LENGTH_LONG).show();
}
});
buttonPlay.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
MediaPlayer mediaPlayer = new MediaPlayer();
try {
mediaPlayer.setDataSource(outputFile);
mediaPlayer.prepare();
mediaPlayer.start();
} catch (Exception e) {
System.out.println("E Catch");
}
Toast.makeText(getApplicationContext(), "Recording Playing", Toast.LENGTH_LONG).show();
}
});
buttonDecode.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//System.out.println(readFile("recording.3gp"));
Toast.makeText(getApplicationContext(), "Decoding", Toast.LENGTH_LONG).show();
//initializes variables
File file = new File(outputFile);
FileInputStream fileInputStream = null;
try {
fileInputStream = new FileInputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
int bytesRead = 0;
int bufferSize = 0;
int bytesAvailable = 0;
byte[] buffer;
int maxBufferSize = 1*1024*1024;
DataOutputStream dos = null;
// create a buffer of maximum size
try {
bytesAvailable = fileInputStream.available();
} catch (IOException e) {
e.printStackTrace();
}
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
// read file and write it into form...
try {
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
} catch (IOException e) {
e.printStackTrace();
}
try{
while (bytesRead > 0){
dos.write(buffer, 0, bufferSize); //<<<<<<<HERE
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
try {
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
} catch (IOException e) {
e.printStackTrace();
}
}
fileInputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
});
//Code for the back button
Button backbuttonR = (Button) findViewById(R.id.backbuttonR);
backbuttonR.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startActivity(new Intent(ReceiveScreen.this, MainActivity.class));
}
});
}
}
