jpetitto

1. Don't blindly accept that Google's approach to Android development is always the right way. Judge for yourself what the right approach is (often times it is Google's approach) based on your requirements and solution.

2. Be comfortable with examining the Android source code. It's not magic, there's always an answer. Helps you solve problems that would otherwise show up on Stackoverflow.

3. Be multi-discipline. Android can be your focus, but develop for other platforms and use other languages.

4. Master the tools. Make it work for you.

5. Be resourceful. Know when and why a library is the right choice over writing your own solution.

jpetitto

Observable.just("Hello, world!")
    .subscribe(new Action1<String>() {
        @Override
        public void call(String s) {
              System.out.println(s);
        }
});

Observable.just("Hello, world!")
    .subscribe(s -> System.out.println(s));

jpetitto

// no DI
public class Refrigerator {
  private PowerSource powerSource;
  
  public Refrigerator() {
    powerSource = new AcPowerSource();
  }
}

// with DI (manual)

jpetitto

public class MainActivity extends AppCompatActivity {
    private Fragment savedFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (savedInstanceState != null) {
            savedFragment = getSupportFragmentManager().getFragment(savedInstanceState, "content");

jpetitto

Enum<E extends Enum<E>> { ... }

<T extends Object & Comparable<? super T>> T Collections.max(Collection<? extends T>) { ... }

public <V extends Wrapper<? extends Comparable<T>>>
  Comparator<V> comparator() { ... }

error: equalTo(Box<capture of ?>) in Box<capture of ?> cannot be applied to (Box<capture of ?>)
  equal = unknownBox.equalTo(unknownBox)

jpetitto

for (int i = 0, remaining = 5; i < colorBucket.size() && remaining > 0; i++, remaining--) {
  ...
}

jpetitto

private <T> int picker(List<T> src, List<T> dst, int limit) {
  Iterator<T> iterator = src.iterator();
  while (iterator.hasNext() && limit > 0) {
    dst.add(iterator.next());
    limit--;
  }
  return limit;
}

jpetitto

List<Item> allBucket = ...
List<Item> genderBucket = ...
List<Item> sizeBucket = ...
List<Item> colorBucket = ...

List<Item> recommendations = new ArrayList<>();
picker(recommendations, limit, colorBucket, sizeBucket, genderBucket, allBucket);

private <T> int picker(List<T> src, List<T> dst, int limit) {
  Iterator<T> iterator = src.iterator();

jpetitto

BehaviorSubject<Integer> timerSubject = BehaviorSubject.create(1);

timerSubject
    .switchMap(interval -> Observable.timer(interval, TimeUnit.SECONDS, Schedulers.newThread()))
    .flatMap(i -> Observable.just(randomInt()))
    .doOnNext(timerSubject::onNext)
    .subscribe(System.out::println);

jpetitto

Observable.just(1, 2, 3, 4, 5)
        .groupBy(i -> i % 2 == 0 ? "even" : "odd")
        .subscribe(obs -> {
            if (obs.getKey().equals("even")) {
                obs.subscribe(i -> System.out.println("even: " + i));
            } else {
                obs.subscribe(i -> System.out.println("odd: " + i));
            }
        });