public class Template {    private final String template;    private final Pattern p = Pattern.compile("\\$\\{(\\w+)\\}");    public Template(String template) {        this.template = template;    }    public String render(Map<String, String> data) {        Matcher m = p.matcher(template);        StringBuffer sb = new StringBuffer();        while (m.find()) {            m.appendReplacement(sb, data.get(m.group(1)));        }        m.appendTail(sb);        return sb.toString();    }    public static void main(String[] args) {        Template t = new Template("Hello, ${name}! You are learning ${lang}!");        Map<String, String> map = Map.of("name", "Bob", "lang", "java");        String s = t.render(map);        System.out.println(s);    }}