javastringcharjava-streamcharsequence

Make a string from an IntStream of code point numbers?

If I am working with Java streams, and end up with an IntStream of code point numbers for Unicode characters, how can I render a CharSequence such as a String? 

String output = "input_goes_here".codePoints(). ??? ;

I have found a codePoints() method on several interfaces & classes that all generate an IntStream of code points. Yet I have not been able to find any constructor or factory method that accepts the same.

I am looking for the converse:

➥ How to instantiate a String or CharSequence or such from an IntStream of code points?

Solution

  • IntStream::collect with StringBuilder

    Use IntStream::collect with a StringBuilder.

    String output = 
    "input_goes_here"
    .codePoints()                            // Generates an `IntStream` of Unicode code points, one `Integer` for each character in the string.
    .collect(                                // Collect the results of processing each code point.
        StringBuilder::new,                  // Supplier<R> supplier
        StringBuilder::appendCodePoint,      // ObjIntConsumer<R> accumulator
        StringBuilder::append                // BiConsumer<R,​R> combiner
    )                                        
    .toString()
;

    If you prefer the more general CharSequence interface over concrete String, simply drop the toString() at the end. The returned StringBuilder is a CharSequence.

    IntStream codePointStream = "input_goes_here".codePoints ();
CharSequence output = codePointStream.collect ( StringBuilder :: new , StringBuilder :: appendCodePoint , StringBuilder :: append );