Android Java 8 Stream API Example

Demo app of using Java 8 features with Retrolambda and Lightweight-Stream-API.

Features:

findViewById(R.id.go).setOnClickListener(v -> {
   final int index = mActionSpinner.getSelectedItemPosition();
   if (index != Spinner.INVALID_POSITION) {
       action(actions[index]);
   }
});

Method::references

int cmp = Objects.compare(word, other.word, String::compareToIgnoreCase);

Stream.API()

return Stream.of(lines)
     .map(str -> str.split("\t"))
     .filter(arr -> arr.length == 2)
     .map(arr -> new Word(arr[0], arr[1]))
     .collect(Collectors.toList());

switch for "string"

switch (action) {
    case "filter 1":
        // Filter one word
        stream = stream.filter(p -> p.getWord().split(" ").length == 1);
        break;
    case "filter 2+":
        // Filter two and more words
        stream = stream.filter(p -> p.getWord().split(" ").length >= 2);
        break;
    // ...
}

try(with-resources) {}

final List<String> lines = new ArrayList<>();
try (final InputStream is = context.getAssets().open("words.txt");
     final InputStreamReader isr = new InputStreamReader(is, "UTF-8");
     final BufferedReader reader = new BufferedReader(isr)) {
    String line;
    while ( (line = reader.readLine()) != null ) {
        lines.add(line);
    }
}

Objects (from Java 7)

@Override
public boolean equals(Object o) {
    // ...
    final Word other = (Word) o;
    return Objects.equals(translate, other.translate) &&
           Objects.equals(word, other.word);
}

@Override
public int hashCode() {
    return Objects.hash(word, translate);
}

~~try {~~ Exceptional ~~} catch~~ (functional try/catch)

return Exceptional.of(() -> {
    final InputStream is = context.getAssets().open("words.txt");
    // ... operations which throws Exception ...
    return lines;
}).ifException(e -> Log.e("Java 8 Example", "Utils.readWords", e))
  .getOrElse(new ArrayList<>());