LowercaseImplement.java

/**
 * LowerConverter implements CaseConverter
 * and converts all words to lower case
 */

class LowerConverter implements CaseConverter {

    @Override
    public String convert(String... words) {

        // Accumulate result in StringBuilder
        StringBuilder result = new StringBuilder();

        // All words are converter to lower
        // And then concatenated
        for (String word : words) {
            result.append(
                word
                   .trim()
                   .toLowerCase());
        }
        return result.toString();
    }
}