This is part of my live blogging from QCon 2015. See my QCon table of contents for other posts.

This session was from the Java Sig. It’s a repeat of the conference session I didn’t attend then since I knew I’d see it here.

Java 8 has lots of new features, but people think of streams/lambdas. This session isn’t slides. It’s building a real app live. Trisha starts with an architecture diagram – small serivces and MVC layer. They aren’t microservices because they aren’t reliable. Then she has a sketch of the screen.

The code is on github.. The master branch is the whole app. There’s also a skeleton branch if you want to try it/play along. The page for this presentation has slides and video.

The Java 8 features I see go by:

• Stub Service uses a Supplier for generating random numbers.
• JavaFX for basic UI. [I’m not familiar with JavaFX.]
• Compute if absent and method reference:

  map.computeIfAbsent("key", TwitterUser::new);

• Streams, comparators

  map.values().stream()
  .sorted(Comparators.comparing(TwitterUser::getTweets)
  .reversed()).limit(10).collect(Collectors.toList();
  

• JavaFX

  laterPlatform.runLater(() -> items.setAll(x));
  

• JavaFX comes with built in animation
• Date/time to get current minute

  LocalDateTime.now().getMinute();
  

• Loop from to y

  IntStream.range(0, 10).forEach(this::method);
  

  This coud be better or worse than a regular loop in terms of readability or performance.

• Read fileStream

  lines = Files.lines(path);
  

• Filter:

  lines.filter(s -> !s.equals("Ok"));
  

• Check on stream:

  lines.peek(s -> method())
  

• Convert array to stream, map

  functionStream.of(arr).map(String:toLowerCase)
  

• Join strings with delimiter in between

  stream.collection(joining(",")
  

Intellij

• automatically shortens to simplest thing that could work making code a method reference or lambda.
• Keyboard shortcut to use appropriate functional interface. Complicated shortcut, but nice function