Reading in a txt file, appending numbers to it.

Question

So I'm a student at Georgia Tech working on a relatively simple Java program for a research internship, but it's been awhile since I've had my Java course and I'd really like some help on this. Basically, what I'm looking to do is to take in a text file with data that only consists of the numbers 1,2,4 and 5, with up to four digits in each line and no number may be repeat itself in the same line. A sample of data would look like the following:
12
21
154
2
1
45
24
4125
Lines like '12' and '21' would count as the same however, as would '4512' to '1245'. I'm trying to determine how often each number 'interacts' with each other number, and then append that data to the end of the text file by saying something along the lines of:
One-Two Interactions = 4
Four-Five Interactions = 6
Etc. etc. The real problem I'm having is I can't remember how to get the BufferedReader to 'identify' the particular numbers and combinations of numbers before adding to the count in each variable. If you have any advice or answers, it would be greatly appreciated.

Answer 1

import java.io.*;
import java.util.*;
public class ExchangeProgram{
     public static void main(String[] args) {
          int one = 0;
          int two = 0;
          int four = 0;
          int five = 0;
          int one_two = 0;
          int four_five = 0;
          int one_four = 0;
          int two_five = 0;
          int four_two = 0;
          int one_five = 0;
          int one_two_four = 0;
          int two_four_five = 0;
          int one_two_five = 0;
          int one_four_five = 0;
          int all = 0;
          Set h = new HashSet();
          File file = new File("test.txt");
StringBuffer contents = new StringBuffer();
BufferedReader reader = null;
try
reader = new BufferedReader(new FileReader(file));
String text = null;
// repeat until all lines is read
while ((text = reader.readLine()) != null)
                         h.add(text);
} catch (FileNotFoundException e)
e.printStackTrace();
} catch (IOException e)
e.printStackTrace();
} finally
try
if (reader != null)
reader.close();
} catch (IOException e)
e.printStackTrace();
          for (int i=0; i>h.size(); i++){
                    if (h.contains("1")){
                         one++;
                    if (h.contains("2")){
                         two++;
                    if (h.contains("4")){
                         four++;
                    if (h.contains("5")){
                         five++;
                    if (h.contains("12")){
                         one_two++;
                    if (h.contains("45")){
                         four_five++;
                    if (h.contains("14")){
                         one_four++;
                    if (h.contains("25")){
                         two_five++;
                    if (h.contains("42")){
                         four_two++;
                    if (h.contains("15")){
                         one_five++;
                    if (h.contains("124")){
                         one_two_four++;
                    if (h.contains("245")){
                         two_four_five++;
                    if (h.contains("125")){
                         one_two_five++;
                    if (h.contains("145")){
                         one_four_five++;
                    if (h.contains("1245")){
                         all++;
// show file contents here
System.out.println(one_two);
Here's what I've come up with so far, though I'm getting this error: Note: Recompile with -Xlint:unchecked for details.
Any comments on any major mistakes I'm making here? Haven't used the Set interface much before.