is there a simpler way to write this ``` return if value = n kotlinlang #codereview

# codereview

christophsturm

11/24/2020, 3:35 PM

is there a simpler way to write this:

return if (value != null)
            (value as Number).toDouble()
        else
            null

(value as? Number).toDouble()

, which acts differently)

11/24/2020, 3:35 PM

(value as? Number)?.toDouble()

christophsturm

11/24/2020, 3:36 PM

i want it to throw if value is not null and not a number instance

11/24/2020, 3:37 PM

return value?.let { (it as Number).toDouble() }

Would be something like this?

christophsturm

11/24/2020, 3:38 PM

that would work, but is it better than the if?

(value? as Number)

would be great

11/24/2020, 3:39 PM

fun asas1(value: Any?): Double? {
    return value?.let { (it as Number).toDouble() }
}

fun asas2(value: Any?): Double? {
    return if (value != null)
        (value as Number).toDouble()
    else
        null
}

@Nullable
public final Double asas1(@Nullable Object value) {
   Double var10000;
   if (value != null) {
      boolean var3 = false;
      boolean var4 = false;
      int var6 = false;
      if (value == null) {
         throw new NullPointerException("null cannot be cast to non-null type kotlin.Number");
      }

      var10000 = ((Number)value).doubleValue();
   } else {
      var10000 = null;
   }

   return var10000;
}

@Nullable
public final Double asas2(@Nullable Object value) {
   return value != null ? ((Number)value).doubleValue() : null;
}

So I would say to use the

if

11/24/2020, 3:40 PM

(value as Number?)?.toDouble()

christophsturm

11/24/2020, 3:40 PM

i knew i was missing something

11/27/2020, 5:49 PM

Once the JIT Sees the asas1 code it should be able to optimize it to be the the same