Reduce.java

import java.util.*;
import java.io.*;
class Reduce
{
    public static void main( String [] args){
        try{
            String ref = args[0];
            String data = args[1];
            FileInputStream fref = new FileInputStream(ref);
            FileInputStream fdata = new FileInputStream(data);
            Set<String> refs = new HashSet<String>();
            DataInputStream in = new DataInputStream(fref);
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            String line;
            while ( ( line = br.readLine () ) != null ){
                refs.add( line );
            }
            in = new DataInputStream(fdata);
            br = new BufferedReader(new InputStreamReader(in));
            while ( ( line = br.readLine () ) != null ){
                String [] tokens = line.split(",");
                if ( !refs.contains ( tokens [0] ) ){
                    System.out.println(line);
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}