README.md

streamx

More or less useful extensions to java.util.stream API mainly for easing consumption of streams backed by IO resources that must be closed.

Example:

// using auto-closing Stream wrapper...

AC.stream(Files.walk(Paths.get("/usr/share/doc")))     // walk paths in directory - close after terminal op.
    .filter(p -> p.toFile().isFile())                  // just take normal files
    .filter(p -> p.toString().endsWith(".txt"))        // and text files among them
    .flatMap(IO.function(                              // wrap IOException with UncheckedIOException
        p -> concat(Stream.of("#", "# " + p, "#"),     // concatenate path name header with
                    Files.lines(p))                    // expanded lines
    ))
    .forEach(System.out::println);                     // print them out (will also close the stream)

// using Streamable functional interface as a factory for streams

Streamable.IO<Path> docs = () -> Files.walk(Paths.get("/usr/share/doc")); // factory of path walk streams

Streamable<String> lines = docs                        // factory of lines streams
    .filter(p -> p.toFile().isFile())                  // just take normal files
    .filter(p -> p.toString().endsWith(".txt"))        // and text files among them
    .flatMap(IO.function(                              // wrap IOException with UncheckedIOException
        p -> concat(Stream.of("#", "# " + p, "#"),     // concatenate path name header with
                    Files.lines(p))                    // expanded lines
    ));

// ... invoke the factory and consume the stream...

lines
    .autoClosingStream()                               // request an auto-closing stream
    .forEach(System.out::println);                     // print them out

// ...or...

try (Stream<String> linesStream = lines.stream()) {    // use try-with-resources on normal stream
    linesStream.forEach(System.out::println);          // print them out
}


// or almost entirely without this extra stuff...

Function<Stream<Path>, Stream<Path>> filterTextFiles = ps ->
    ps.filter(p -> p.toFile().isFile())                // just take normal files
      .filter(p -> p.toString().endsWith(".txt"));     // and text files among them

Function<Stream<Path>, Stream<String>> dumpLines = ps ->
    ps.flatMap(
        IO.function(                                   // wrap IOException with UncheckedIOException
            p -> concat(Stream.of("#", "# " + p, "#"), // concatenate path name header with
                        Files.lines(p))                // expanded lines
        )
    );

Consumer<Stream<String>> printLines = ls -> ls.forEach(System.out::println);

// ... apply this lazy transformations...

printLines.andThen(Stream::close)
    .accept(
        filterTextFiles.andThen(dumpLines)
            .apply(
                Files.walk(Paths.get("/usr/share/doc"))
            )
    );