Search manager for lists

SearchManager.java

import java.text.Normalizer;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.StringTokenizer;

/**
 * Created by Muzaffer YILMAZ on 28.2.2018.
 */
public class SearchManager<T extends SearchManager.Searchable> {

    public interface Searchable {
        String[] getSearchableFields();
    }

    private ArrayList<T> mList;
    private static final int MIN_WORD_LENGTH = 1;

    public SearchManager(ArrayList<T> list) {
        mList = list;
    }

    public List<T> getFilteredList(String expr) {

        LinkedList<String> tokens = getTokens(expr);

        // if there is an suitable expression
        if (tokens == null || tokens.size() == 0) {
            return mList;
        }

        ArrayList<T> retList = new ArrayList<>();
        for (T item : mList) {
            // search each token of expression
            boolean found = false;
            for (String token : tokens) {
                // if any word is found, add return list
                for (String field : item.getSearchableFields()) {
                    if (isContain(field, token)) {
                        retList.add(item);
                        found = true;
                        break;
                    }
                }
                if (found) break;
            }
        }

        return retList;
    }

    private String normalize(String token) {
        // normalize string: iğüş -> IGUS
        String normalizedToken = Normalizer.normalize(token, Normalizer.Form.NFD);
        normalizedToken = normalizedToken.replaceAll("(?s)\\p{InCombiningDiacriticalMarks}", "");
        return normalizedToken;
    }

    private LinkedList<String> getTokens(String expr) {

        StringTokenizer tokenizer = new StringTokenizer(expr, " ");
        LinkedList<String> tokens = new LinkedList<>();

        while (tokenizer.hasMoreTokens()) {
            String token = normalize(tokenizer.nextToken().toLowerCase());
            if (token.length() >= MIN_WORD_LENGTH) {
                tokens.add(token);
            }
        }

        return tokens;
    }

    private boolean isContain(String item, String expr) {
        return item != null && normalize(item.toLowerCase()).contains(expr);
    }
}