Thank You so much for pointing out the importance of using a Buffer. The code I used below was so very slow.
String wavFile1 = "C:\\1.mp3";
String wavFile2 = "C:\\2.mp3";
FileInputStream fistream1 = new FileInputStream(wavFile1); // first source file
FileInputStream fistream2 = new FileInputStream(wavFile2);//second source file
SequenceInputStream sistream = new SequenceInputStream(fistream1, fistream2);
FileOutputStream fostream = new FileOutputStream("D://merge1.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();
so tried the buffer and it improved 100%