问确定性有限自动机- Java

EN

import java.io.*;
import java.util.ArrayList;

public class Task
{

public static void main(String[] args) throws FileNotFoundException, IOException 
{
    BufferedReader reader = new BufferedReader(new FileReader("file.txt ")); 
    ArrayList<String> wordList = new ArrayList<>();

    String line = null;

    while ((line = reader.readLine()) != null) 
    {
        wordList.add(line);
    }

    for (String word : wordList) 
    {
        if (word.matches("^a"))
        {   
            if (word.matches("ab") || word.matches("^ac"))
            {
                 System.out.print(word+" - OK\n");
            }
            else
            {
                System.out.print(word+" - STOP (word doesn't exists in alphabet)\n");
                System.exit(0);
            }
        }
    }
   }
}