Whenever you want to return a value from a method, but whatever you return depends on some other value, you typically use branching:

int calculateSomething() {
  if (a == b) {
    return x;
  } else {
    return y;
  }
}

Another way to write this is:

int calculateSomething() {
  if (a == b) {
    return x;
  }
  return y;
}

Is there any reason to avoid one or the other? Both allow adding "else if"-clauses without problems. Both typically generate compiler errors if you add anything at the bottom.

Note: I couldn't find any duplicates, although multiple questions exist about whether the accompanying curly braces should be on their own line. So let's not get into that.