Re: New VSI post on Youtube

On 8/24/2024 10:04 PM, Arne Vajhøj wrote:

$ type OptionalDemo.java
import java.util.Optional;
 public class OptionalDemo {

...

     public static void main(String[] args) {
         testOldStyleAPI(123);
         testOldStyleAPI(0);
         testNewStyleAPI(123);
         testNewStyleAPI(0);
         testNewStyleAPISmarter(123);
         testNewStyleAPISmarter(0);
     }
}
$ javac OptionalDemo.java
$ java "OptionalDemo"
123
No result
123
No result
123
No result

The code becomes a little shorter in Kotlin.
$ type OptionalDemo.kt
import java.util.*
fun oldStyleAPI(v: Int): String? {
   return if(v > 0) v.toString() else null;
}
fun newStyleAPI(v: Int): Optional<String> {
   return if(v > 0) Optional.of(v.toString()) else Optional.empty();
}
fun testOldStyleAPI(v: Int) {
   println(oldStyleAPI(v) ?: "No Result")
}
fun testNewStyleAPI(v: Int) {
   println(newStyleAPI(v).orElse("No Result"))
}
fun main() {
   testOldStyleAPI(123)
   testOldStyleAPI(0)
   testNewStyleAPI(123)
   testNewStyleAPI(0)
}
$ kotlinc "OptionalDemo.kt"
$ kotlin "OptionalDemoKt"
123
No Result
123
No Result
Kotlin 1.9.10 on VMS x86-64. Works fine - just make sure
the source files are in stmlf format!
Arne