How to replace the method with Java 8 streams?

Question

It can be an obvious question but I am thinking how to replace the method below with java 8 streams.

private String assembleString(int numberOfCharacters, char character) {
    StringBuilder stringBuilder = new StringBuilder();
    for (int i = 0; i < numberOfCharacters; i++) {
        stringBuilder.append(character);
    }
    return stringBuilder.toString();
}

I am new in Java, so java 8 it is like an unexplored world for me.

Thank you!

Answer 1

All you need is just Collections.nCopies

private static String assembleString(int numberOfCharacters, char character) {
    return String.join("",
            Collections.nCopies(numberOfCharacters, String.valueOf(character))
    );
}

Answer 2

You can use Stream.generate:

return Stream.generate(() -> String.valueOf(character))
              .limit(numberOfCharacters)
              .collect(Collectors.joining());

or IntStream.rangeClosed:

return IntStream.rangeClosed(1, numberOfCharacters)
                .mapToObj(n -> String.valueOf(character))
                .collect(Collectors.joining());