converting List type with Lambda Java

Question

If I have an expression:

  / List<Long> /                   / List<String> /
s.getPhones().addAll(Arrays.asList(rs.getString("phones").split(",")));

Can I use Java Lambda to convert types with Long.parseLong in pritty form without "for loop" ? Or even if will use for loop, it will became more "codeless".

How it must look like?

Answer 1

You can convert the List<String> to a Stream , map the elements to Long , then collect them back to a List<Double> that is suitable to pass to addAll on s.getPhones() . No lambda expression is necessary because of the method reference, but streams makes this easier.

s.getPhones().addAll(
    Arrays.asList("123,456,789".split(","))
        .stream()
        .map(Long::valueOf)  // You could use: (s -> Long.valueOf(s))
        .collect(Collectors.toList()));