要求失败，并带有浮点数

Question

private void waveformProgress(double currentProgressPercentage) {
   if (currentProgressPercentage < 0.0f) currentProgressPercentage = 0.0f;
   if (currentProgressPercentage > 1.0f) currentProgressPercentage = 1.0f;
   waveView.setProgress((float) (100.0 * currentProgressPercentage));
   ..
 }

I have rare crash reports on the setProgress line, in the call to a kotlin setter:

var progress: Float = 0F
        set(value) {
            require(value in 0..100) { "Progress must be in 0..100" }
...
        }

I know about floating point equality and all, but how is it possible that the require fails here? How would I correct it? I suppose it's possible Crashlytics is reporting new version number when the crash happened in old version that didn't ensure the number was between 1..100.

Answer 1

There is a currentProgressPercentage for which you should get this exception: NaN (it isn't actually a single value, but this doesn't matter here). Both comparisons will be false, and (float) (100.0 * currentProgressPercentage) will return a NaN which isn't in range 0..100 . A NaN can be produced, eg, by calculating 0.0/0.0 .