使用Java 8 API，根据传递的分隔符，连接list中所有的元素

public class MethodReferenceDemo1 {

@FunctionalInterface

interface StringListFormatter {

String format(String delimiter, List<String> list);

}

public static void formatAndPrint(StringListFormatter formatter,  String delimiter, List<String> list) {

String formatted = formatter.format(delimiter, list);

System.out.println(formatted);

}

public static void main(String[] args) {

List<String> names = Arrays.asList("Don", "King", "Kong");

formatAndPrint(String::join, ", ", names);

}

}