pattern.compile help java program

Question

I have written a program to parse a text file which contains a sample C program with if, else and while condition.

I have 2 ArrayLists and my program will parse through the file. I'm using Matcher and have specified pattern Strings in Pattern.compile(). I am trying to draw a control flow graph for a particular program; however, I'm just finding the nodes for now and will link them up later.

Here is my code:

//import static LineMatcher.ENCODING;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.LineNumberReader;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public final class CFG {

  public void findLines(String aFileName) {
    List<Integer> a = new ArrayList<Integer>();
    List<Integer> b = new ArrayList<Integer>();
    // int [] a = new int[10000];
    // int [] b = new int[10000];
    Pattern regexp = Pattern.compile("if|else|while");
    Matcher exp1 = regexp.matcher("if");
    Matcher exp2 = regexp.matcher("else");
    Matcher exp3 = regexp.matcher("while");

    Path path = Paths.get(aFileName);
    try (BufferedReader reader = Files.newBufferedReader(path, ENCODING);
        LineNumberReader lineReader = new LineNumberReader(reader);) {
      String line = null;
      while ((line = lineReader.readLine()) != null) {
        // exp1.reset(line); //reset the input
        int counter = 1;
        if (exp1.find()) {
          int l = lineReader.getLineNumber();

          b.add(l);
        }
        if (exp2.find()) {
          int l = lineReader.getLineNumber();

          b.add(l);
        }
        if (exp3.find()) {
          int l = lineReader.getLineNumber();

          b.add(l);
        } else {
          int l = lineReader.getLineNumber();
          a.add(l);
        }
      }
      // counter++;

      System.out.println(a);
      System.out.println(b);
    }

    catch (IOException ex) {
      ex.printStackTrace();
    }
  }

  final static Charset ENCODING = StandardCharsets.UTF_8;

  public static void main(String... arguments) {
    CFG lineMatcher = new CFG();
    lineMatcher.findLines("C:Desktop\\test.txt");
  }
}

What I'm trying to do here is, if my String is found, enter the line number in ArrayList b, otherwise enter the line number in ArrayList a. Hence, I know, which lines have if, else and while statements.

I don't know if my code is incorrect or what, the input file is as below :

#include <stdio.h>

int main()
{
  int i=1, sum = 0;  
  if( i = 1)  {
    sum += i;
  }  else
    printf("sum = %d\n", sum);

  return 0;
}

and the output of the program is:

run: 
[2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]
[1, 1, 1]

PS: I'm an amateur, this program could be logically incorrect.

Please let me know if any more information is needed.

EDIT :

Code that works fine for just one string search :

Pattern regexp = Pattern.compile("if");
    Matcher matcher = regexp.matcher("if");


    Path path = Paths.get(aFileName);
    try (
      BufferedReader reader = Files.newBufferedReader(path, ENCODING);
      LineNumberReader lineReader = new LineNumberReader(reader);
    ){
      String line = null;
      while ((line = lineReader.readLine()) != null) {
       matcher.reset(line); //reset the input


       if(matcher.find())
       {

         int a= lineReader.getLineNumber();
         System.out.println(a);
                }

      }      
    }    
    catch (IOException ex){
      ex.printStackTrace();
    }

Above one works fine(its just a part of code, not entire program. program is same as above one) and returns the line number where if is found. I used same logic and added the else and while part.

Answer 1

Finally, I got this working (Thanks for the amazing inputs). below are the changes I made :

public void findLines(String aFileName) {

     List<Integer> a = new ArrayList<Integer>();
     List<Integer> b = new ArrayList<Integer>();

    Pattern regexp = Pattern.compile("(if|else|while).*");
    Matcher exp1 = regexp.matcher("if|else|while");
    Path path = Paths.get(aFileName);
        try (
          BufferedReader reader = Files.newBufferedReader(path, ENCODING);
          LineNumberReader lineReader = new LineNumberReader(reader);
        ){
          String line = null;
          while ((line = lineReader.readLine()) != null) {
          exp1.reset(line); 


            if(exp1.find())
            {
                int l= lineReader.getLineNumber();


                b.add(l);

                     }

            else
            {int l= lineReader.getLineNumber();
                  a.add(l);


               }   

          } 


        System.out.println(a);
        System.out.println(b);
                }


       catch (IOException ex){
         ex.printStackTrace();
        }

The input file is same and the output is :

[1, 2, 3, 4, 6, 7, 8, 10, 11, 12, 13]
[5, 9]