error java.lang.ArrayIndexOutOfBoundsException: length=166074; index=166074

Question

I am trying to merge two MP3 files to a single MP3 file. The files are saved in an SD card but it can't be played. First, I converted the MP3 to WAV file stored in /res/raw folder, and output it on SD card. It also gives ArrayOutOfBoundsException.

public class MainActivity extends Activity {

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

        // MediaPlayer mediaPlayer= MediaPlayer.create(getApplicationContext(),getAssets()+"" )

        try {
            mixSound();
        } catch (Exception e) {
            // TODO Auto-generated catch block
        e.printStackTrace();
        }
    }

    private void mixSound()  {
        try {
            AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, 44100,       AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT, 44100, AudioTrack.MODE_STREAM);

            // Uri url = Uri.parse("android.resource://" + getPackageName() + "/" +    R.raw.one);
            // System.out.println("MainActivity.mixSound() url1"+url.toString());
            // File file = new File(url.toString());
            // Uri url2 = Uri.parse("android.resource://" + getPackageName() + "/" + R.raw.two);
            // System.out.println("MainActivity.mixSound() url1"+url2.toString());
            // File file2 = new File(url2.toString());

            // InputStream in1=new FileInputStream(file);      
            // InputStream in2=new FileInputStream(file2); 

            // int rid = getResources().getIdentifier(getPackageName() + ":raw/one.mp3" , null, null);  
            // get the file as a stream  
            // InputStream in1 = getResources().openRawResource(rid);
            // InputStream in1=new FileInputStream(""); 
            //      
            // int rid2 = getResources().getIdentifier(getPackageName() + ":raw/two.mp3" , null, null);  
            // get the file as a stream  
            // InputStream in2 = getResources().openRawResource(rid2);
            //      
            // InputStream in2=new  FileInputStream(getResources().openRawResource(R.raw.one).toString()); 

            InputStream in1 = getApplicationContext().getResources().openRawResource(R.raw.media);
            InputStream in2 = getApplicationContext().getResources().openRawResource(R.raw.media1);

            byte[] music1 = null;
            music1= new byte[in1.available()]; 
            music1=convertStreamToByteArray(in1);
            in1.close();

            byte[] music2 = null;
            music2= new byte[in2.available()]; 
            music2=convertStreamToByteArray(in2);
            in2.close();

            byte[] output = new byte[music2.length];

            audioTrack.play();
            int j=0;
            for(int i=0; i < output.length; i++){
                float mixed;
                if(j<music1.length){
                    float samplef1 = music1[j] / 128.0f; // 2^7=128
                    float samplef2 = music2[i] / 128.0f;
                    mixed = samplef1 + samplef2;
                    j++;
                }else{
                    float samplef2 = music2[i] / 128.0f;
                    mixed = samplef2; 
                }

                float samplef1 = music1[j] / 128.0f; // 2^7=128
                float samplef2 = music2[i] / 128.0f;
                mixed = samplef1 + samplef2;

                // reduce the volume a bit:
                mixed *= 0.8;
                // hard clipping
                if (mixed > 1.0f) mixed = 1.0f;

                if (mixed < -1.0f) mixed = -1.0f;

                byte outputSample = (byte)(mixed * 128.0f);
                output[i] = outputSample;
            }

            audioTrack.write(output, 0, output.length);

            //convert array of bytes into file
            FileOutputStream fileOuputStream = new FileOutputStream(Environment.getExternalStorageDirectory()+"/abc.wav"); 
            fileOuputStream.write(output);
            fileOuputStream.close();
            System.out.println("MainActivity.mixSound()==>Done");
            System.out.println("Done");
        }catch(Exception e){
            //  e.printStackTrace();
            System.out.println("MainActivity.mixSound()==>"+e);
        }
    }

    public static byte[] convertStreamToByteArray(InputStream is) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buff = new byte[10240];
        int i = Integer.MAX_VALUE;
        while ((i = is.read(buff, 0, buff.length)) > 0) {
            baos.write(buff, 0, i);
        }

        return baos.toByteArray(); // be sure to close InputStream in calling function
    }
}

Answer 1

ArrayOutOfBoundException is in code line

for(int i=0; i < output.length; i++)

it should be

for(int i=0; i < output.length-1; i++)

Also as suggested by grattmandu03 below code

if(j<music1.length)

should be

if(j<music1.length-1)

Answer 2

With a length of 166074 the last index to access is (166074 - 1) The arrays starts with element 0. (zero offset)