Reading & writing to file using ArrayList String incorrectly (2)

Question

I have been able to store two strings (M44110|T33010, M92603|T10350) using ArrayList<String>, which represent the result of some patient tests. Nevertheless, the order of these results have been stored correctly.
E.g. currently stored in file Snomed-Codes as -
[M44110|T33010, M92603|T10350][M44110|T33010, M92603|T10350]
Should be stored and printed out as -
M44110|T33010
M92603|T10350
Below is the detail of the source code of this program:
import java.io.*;
import java.io.IOException;
import java.lang.String;
import java.util.regex.*;
import java.util.ArrayList;
public class FindSnomedCode {
    static ArrayList<String> allRecords = new ArrayList<String>();
    static public ArrayList<String> getContents(File existingFile) {
        StringBuffer contents = new StringBuffer();
        BufferedReader input = null;
        int line_number = 0;
        int number_of_records = 0;
        String snomedCodes = null;
        ArrayList<String> complete_records = new ArrayList<String>();
        try {
            input = new BufferedReader( new FileReader(existingFile) );
            String current_line = null;
            while (( current_line = input.readLine()) != null) {
                // Create a pattern to match for the "\"
                Pattern p = Pattern.compile("\\\\");
                // Create a matcher with an input string
                Matcher m = p.matcher(current_line);
                boolean beginning_of_record = m.find();
                if (beginning_of_record) {
                    line_number = 0;
                    number_of_records++;
                } else {
                    line_number++;
                if ( (line_number == 2) && (current_line.length() != 0) ) {
                    snomedCodes = current_line;
                    System.out.println(snomedCodes);
                    complete_records.add(current_line);
        catch (FileNotFoundException ex) {
            ex.printStackTrace();
        catch (IOException ex){
            ex.printStackTrace();
        finally {
            try {
                if (input!= null) {
                    input.close();
            catch (IOException ex) {
                ex.printStackTrace();
        return complete_records;
    static public void setContents(File reformatFile, ArrayList<String> snomedCodes)
                                 throws FileNotFoundException, IOException {
       Writer output = null;
        try {
            output = new BufferedWriter( new FileWriter(reformatFile) );
              for (String index : snomedCodes) {
                  output.write( snomedCodes.toString() );
        finally {
            if (output != null) output.close();
    static public void printContents(File existingFile) {
        StringBuffer contents = new StringBuffer();
        BufferedReader input = null;
        int line_number = 0;
        int number_of_records = 0;
        String snomedCodes = null;
        try {
            input = new BufferedReader( new FileReader(existingFile) );
            String current_line = null;
            while (( current_line = input.readLine()) != null)
                System.out.println(current_line);
        catch (FileNotFoundException ex) {
            ex.printStackTrace();
        catch (IOException ex){
            ex.printStackTrace();
        finally {
            try {
                if (input!= null) {
                    input.close();
            catch (IOException ex) {
                ex.printStackTrace();
    public static void main (String args[]) throws IOException {
        File currentFile = new File("D:\\dummy_patient.txt");
        allRecords = getContents(currentFile);
        File snomedFile = new File( "D:\\Snomed-Codes.txt");
        setContents(snomedFile, allRecords);
        printContents(snomedFile);
}There are 4 patient records in the dummy_patient.txt file but only the 1st (M44110|T33010) & 3rd (M92603|T10350) records have results in them. The 2nd & 4th records have blank results.
Lastly, could someone explain to me the difference between java.util.List & java.util.ArrayList?
I am running Netbeans 5.0, jdk1.5.0_09 on Windows XP, SP2.
Many thanks,
Netbeans Fan.

Answer 1

while (snomedCodes.iterator().hasNext())
  output.write( snomedCodes.toString() );
}Here you have some kind of a list or something (I couldn't stand to read all that unformatted code but I suppose you can find out). It has an iterator which gives you the entries of the list one at a time. You keep asking if it has more entries -- which it does -- but you never get those entries by calling the next() method, so it always has all the entries still available.
And your code inside the loop is independent of the iterator, so it's rather pointless to iterate over the entries and output exactly the same data for each entry. Even if you were iterating correctly.