is there a simpler way to write this: ``` return if (value != null) (value as Num...

# codereview

[christophsturm]

is there a simpler way to write this:

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

(not (value as? Number).toDouble() , which acts differently)

[wbertan]

(value as? Number)?.toDouble()

[christophsturm]

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

[wbertan]

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

Would be something like this?

[christophsturm]

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

[christophsturm]

(value? as Number) would be great

[wbertan]

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
}

Generates:

@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 🙃

[Joris PZ]

What about (value as Number?)?.toDouble() ?

[christophsturm]

thanks!!

[christophsturm]

i knew i was missing something

[Kroppeb]

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