Say I have `fun myCheck(): Boolean` which I want t...

# getting-started

[Mark]

Say I have fun myCheck(): Boolean which I want to repeatedly call until it returns false. If I use while (myCheck()) {} then I get a warning saying “control flow with empty body”. So I guess while is supposed to be used with a non-empty body. Does this mean there is a more appropriate way?

[Francisco Javier Ruiz Rodriguez]

Yep, It seems you want to run some code while your condition is true, so put your code inside the while

[Mark]

But there is no code to run while the condition is true. The check does all that is needed.

[Francisco Javier Ruiz Rodriguez]

So you can try this:

do {
        val bool = myCheck()
    }while(bool)

[elizarov]

Write a comment inside that it is intentionally empty.

[Mark]

var index = start
while (myCheck(index++)) { /* nothing to do */ }

Very much a style question, but I just wonder if there is a neater way - probably a for loop so that index is encapsulated, but then the code is maybe too verbose.

[arve]

var index = start
while (myCheck(index++)) { continue; }

[Mark]

The equivalent of in Java;

for (int index = start; myCheck(index); index++) { /*do nothing */ }

[kyleg]

There’s also

generateSequence(start){ it+1 }.takeWhile(::myCheck).count()

if you want to be kooky. :)

[James Richardson]

Spinning on a check like this is not very good for battery life or energy consumption. The check could be executed millions of times a second. Have you considered some other synchronisation method. E.g. condition variable, countdown latch....