Thread: Help with Beginner JAVA method!

Hi guys I can't seem to get this method working. Any help is appreciated on what's wrong in my code thanks!

    /**
public static final String SENTENCE_SEPARATORS = "[.?!]";
 
     * Given an ArrayList of lines from a text file, create a new array list
     * in which each entry is a sentence from the file 
     * with SENTENCE_SEPARATORS removed but no other changes.
     * A sentence is defined to be a sequence of characters that 
     * (1) is terminated by (but doesn't include) the characters ! ? . or the end of the file, 
     * (2) excludes whitespace on either end, and 
     * (3) is not empty.
     */
    public static ArrayList<String> convertFileLinesToSentences(ArrayList<String> filelines)
    {
        String allLines = "";
        for(String lines : filelines) { // add all lines into a single string
            allLines = (lines + " ");
        }
        String[] sentencesArray = allLines.split(SENTENCE_SEPARATORS);  // split at sentence separators
        ArrayList<String> entries = new ArrayList<>(Arrays.asList(sentencesArray)); // add sentences from array into ArrayList
        for(String sentence : entries) { // remove the sentence separators
            sentence.trim().replaceAll(SENTENCE_SEPARATORS, "");
        }
        return entries;
    }