SpellCheck.java

import java.util.ArrayList;

/*This code was copied from user drewmore on StackOverflow,
 * with some slight alterations to the base. If you would like to find the original code,
 * you can find it at 
 * https://codereview.stackexchange.com/questions/48908/java-implementation-of-spell-checking-algorithm
 */

public class SpellCheck {

    private dictionary dict;
    final static String filePath = "english-words.35";
    final static char[] alphabet = "abcdefghijklmnopqrstuvwxyz".toCharArray();

    SpellCheck() {
        dict = new dictionary();
        dict.build(filePath);

    }

    boolean run(String input) {
        while (true) {
            if (input.equals("")) {
                break;
            }
            if (dict.contains(input)) {
                continue;
            } else {
                System.out.print(input + "is not spelled correctly.");
                return false;
            }
            
        }
        return true;
    }

    String printSuggestions(String input) {
        StringBuilder sb = new StringBuilder();
        ArrayList<String> print = makeSuggestions(input);
        if (print.size() == 0) {
            return "and I have no idea what word you could mean.\n";
        }
        sb.append("perhaps you meant:\n");
        for (String s : print) {
            sb.append("\n  -" + s);
        }
        return sb.toString();
    }

    private ArrayList<String> makeSuggestions(String input) {
        ArrayList<String> toReturn = new ArrayList<>();
        toReturn.addAll(charAppended(input));
        toReturn.addAll(charMissing(input));
        toReturn.addAll(charsSwapped(input));
        return toReturn;
    }

    private ArrayList<String> charAppended(String input) { 
        ArrayList<String> toReturn = new ArrayList<>();
        for (char c : alphabet) {
            String atFront = c + input;
            String atBack = input + c;
            if (dict.contains(atFront)) {
                toReturn.add(atFront);
            }
            if (dict.contains(atBack)) {
                toReturn.add(atBack);
            }
        }
        return toReturn;
    }

    private ArrayList<String> charMissing(String input) {   
        ArrayList<String> toReturn = new ArrayList<>();

        int len = input.length() - 1;
        //try removing char from the front
        if (dict.contains(input.substring(1))) {
            toReturn.add(input.substring(1));
        }
        for (int i = 1; i < len; i++) {
            //try removing each char between (not including) the first and last
            String working = input.substring(0, i);
            working = working.concat(input.substring((i + 1), input.length()));
            if (dict.contains(working)) {
                toReturn.add(working);
            }
        }
        if (dict.contains(input.substring(0, len))) {
            toReturn.add(input.substring(0, len));
        }
        return toReturn;
    }

    private ArrayList<String> charsSwapped(String input) {   
        ArrayList<String> toReturn = new ArrayList<>();

        for (int i = 0; i < input.length() - 1; i++) {
            String working = input.substring(0, i);// System.out.println("    0:" + working);
            working = working + input.charAt(i + 1);  //System.out.println("    1:" + working);
            working = working + input.charAt(i); //System.out.println("    2:" + working);
            working = working.concat(input.substring((i + 2)));//System.out.println("    FIN:" + working); 
            if (dict.contains(working)) {
                toReturn.add(working);
            }
        }
        return toReturn;
    }

}