Merge text files

Question

Hey all,
I've got two text files that need to be merged into another text file. One is a template where I have to insert various things, and one is list of the things I have to insert. I am familiar with BufferedReader and PrintWriter etc but was wondering on some tips on how to do it.
eg in the template.txt
I have
<<name>> <<address>>
Welcome, <<name>>, you live at <<addresss>>.
in the list.txt I have the name and address with delimiters which I believe you use Tokenizer for.
i have
Peter%n%
60 Black Road%a&
What is the order of things to process this and merge data in another text file?
Thanks for help.

Answer 1

Hi,
Here comes a complete example, but it differs from the approach ChuckBing gave you. I think this is more generic, has speed advantages, and is easier to adapt/maintain to other situations.
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
class Test {
    public static void main(String[] args) throws Exception {
        //Setup the generator
        //You want to read template from a file.       
        String template = "Welcome, <<name>>, you live at <<addresss>>"; 
        MessageGenerator generator = new MessageGenerator(template, "<<.*?>>");
        Record record = new Record();
        //Register callbacks for all tokens that you are interested in.
        generator.registerCallback("<<name>>", new AbstractCallback(record) {
            public String getValue(String token) {
                return record.getName();
        generator.registerCallback("<<addresss>>", new AbstractCallback(record) {
            public String getValue(String token) {
                return record.getAddress();
        //And test it.. You probably want to change this to a loop that
        //reads records, and writes the result to a file.
        record.setData("Kaj Bjurman%Any adress 21%");
        System.out.println(generator.getResult());
        record.setData("Another name%Another adress%");
        System.out.println(generator.getResult());
* Generates messages using a template, and callbacks
* @author Kaj Bjurman
class MessageGenerator {
    private String template;
    private Pattern pattern;
    private int previousMatchIndex;
    private Matcher matcher;
    private Map callbacks;   // Map<String token, Callback callback>
    private StringBuffer result;
    public MessageGenerator(String template, String tokenPattern) {
        this.template = template;
        this.pattern = Pattern.compile(tokenPattern);
        callbacks = new HashMap();
    public void reset() {
        previousMatchIndex = 0;
        matcher = pattern.matcher(template);
        result = new StringBuffer();
    public void registerCallback(String token, Callback callback) {
        callbacks.put(token, callback);
    public String getResult() {
        reset();
        while (matcher.find()) {
            result.append(template.substring(previousMatchIndex, matcher.start()));
            previousMatchIndex = matcher.end();
            String token = matcher.group();
            Callback callback = (Callback)callbacks.get(token);
            String value = token;
            if (callback != null) {
                value = callback.getValue(token);
            result.append(value);
        result.append(template.substring(previousMatchIndex));
        return result.toString();
    public static interface Callback {
        String getValue(String token);
* Class that represents a record of data.
* The data is expected to be in the form field1%field2%
* @author Kaj Bjurman
class Record {
    private String name;
    private String address;
    public void setData(String data) {
        String[] tmp = data.split("%");
        name = tmp[0];
        address = tmp[1];
    public String getName() {
        return name;
    public String getAddress() {
        return address;
* @author Kaj Bjurman
abstract class AbstractCallback implements MessageGenerator.Callback {
    protected Record record;
    public AbstractCallback(Record record) {
        this.record = record;
}/Kaj