CaseAngel.java

/**
 * Our EVIL code has turned into an angel
 * We now have a small and maintanable code
 */
 
class Angel {

    // Get rid of old switch-case/if-else ladder
    // Replace it with a sweet map
    HashMap<String, CaseConverter> converters =
            (HashMap<String, CaseConverter>)
            Map.of(
                    "lower", new LowerConverter(), 
                    "camel", new CamelConverter()
           );

    public String changeCase(String caseType, String... words) {

        // We support lower and camel cases
        // Sanitize the user input
        caseType = caseType
                .trim()
                .toLowerCase();

        // Lookup which converter the user wants
        CaseConverter converter = converters.get(caseType);
        if (converter!=null)
            return converter.convert(words);
        else 
            return null;
    }

    public static void main(String[] args) {
        Angel obj = new Angel();
        String output = obj.changeCase("camel", "This", "Word");
        System.out.println(output);
    }
}