import java.io.File;
import java.io.FileNotFoundException;
import java.util.LinkedList;
import java.util.Scanner;

public class Test{

    public static void main(String [] args){
        LinkedList<String> list = turnSentencesToList("sampleFile.txt");

        for(String s: list)
            System.out.println(s);
    }


    public static LinkedList<String> turnSentencesToList(String fileName) {
        LinkedList<String> list = new LinkedList<>();

        File file = new File(fileName);
        Scanner scan;
        try {
            scan = new Scanner(file);
            while(scan.hasNextLine()){
                String line = scan.nextLine().trim();

                String[] sentences = null;
                //we don't need empty lines
                if(!line.equals("")) {
                    //splits by . or ! or ?
                    sentences = line.split("\.|!|\?");

                    if(sentences!=null) {
                        for(String s: sentences) {
                            list.add(s.trim());
                        }
                    }
                }
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            return null;
        }
        return list;
    }
}

Sample textfile
A man, l, a ballot, a catnip, a pooh, a rail, a calamus, a dairyman, a bater, a canal - Panama
This is a sentence
This one also
Heres another one
Yes another one