Assignment not allowed in while expression?

Question

In Java we can usually perform an assignment within the while condition. However Kotlin complains about it. So the following code does not compile:

Answer 1

And here is a short Kotlin-style general solution by Roman Elizarov:

while (true) {
    val line = reader.readLine() ?: break
    println(line);
}

Here break has Nothing type that also helps to promote type inference for the line as non-nullable string.