StringManipulation.java

public class StringManipulation {

    public String trimAndConcat(String string1, String string2) {
        return string1.trim().concat(string2.trim());
    }

    public Integer getIndexOrNull(String input, char c) {
        if (input.indexOf(c) == -1) {
            return null;
        }
        return input.indexOf(c);
    }

    public Integer getIndexOrNull(String input, String sub) {
        if (input.indexOf(sub) == -1) {
            return null;
        }
        return input.indexOf(sub);
    }

    public String concatSubstring(String input, int idxA, int idxB, String replacement) {
        String substr;
        try {
            substr = input.substring(idxA, idxB);
        } catch (IndexOutOfBoundsException e) {
            System.out.println(String.format("Exception caught: %s", e));
            substr = "whoops!";
        }

        return substr.concat(replacement);
    }
}