New to Java

I used InputStream for reading socket. I need flush InputStream object before reading socket in second time. Below I show my code sample.Anyone can give me any hints. Thank you

InputStream inReader=sock.getInputStream();
int rc=inReader.read(msgBuf,0,128);

//I want flush here before read again

int secondRecMsg=inReader.read(secondRecMsgBuf,0,128);