How to merge two mp3 files into one (combine/join)

import java.io.*;
public class TwoFiles
{
    public static void main(String args[]) throws IOException
    {
        FileInputStream fistream1 = new FileInputStream("C:\\Temp\\1.mp3");  // first source file
        FileInputStream fistream2 = new FileInputStream("C:\\Temp\\2.mp3");//second source file
        SequenceInputStream sistream = new SequenceInputStream(fistream1, fistream2);
        FileOutputStream fostream = new FileOutputStream("C:\\Temp\\final.mp3");//destinationfile

        int temp;

        while( ( temp = sistream.read() ) != -1)
        {
            // System.out.print( (char) temp ); // to print at DOS prompt
            fostream.write(temp);   // to write to file
        }
        fostream.close();
        sistream.close();
        fistream1.close();
        fistream2.close();
    }
}

Consider two cases for .mp3 files:

• Files with same sampling frequency and number of channels

In this case, we can just append the second file to end of first file. This can be achieved using File classes available on Android.

• Files with different sampling frequency or number of channels.

In this case, one of the clips has to be re-encoded to ensure both files have same sampling frequency and number of channels. To do this, we would need to decode MP3, get PCM samples,process it to change sampling frequency and then re-encode to MP3. From what I know, android does not have transcode or reencode APIs. One option is to use external library like lame/FFMPEG via JNI for re-encode.