Kotlin “also” function strange warning in Android Studio

问题

There is two presumably identical snippets:

// Verbose version
val typedArray = context.obtainStyledAttributes(attrs, styleable)
block(typedArray)
typedArray.recycle()

// One-line version
context.obtainStyledAttributes(attrs, styleable).also(block).recycle()

I'm wonder why verbose block of code looks fine to Android Studio, whereas one-line version highlights obtainStyledAttributes and gives following warning:

This TypedArray should be recycled after use with #recycle()

Does anyone know is it just an Android Studio lint check flaw or something is actually wrong with one-line version?

回答1:

This is a bit of a guess, but I believe it's because the static analysis tool can't guarantee that the TypedArray returned by also() is the same instance as the one returned by obtainedStyledAttributes(). It sees that a TypedArray is obtained but can't guarantee that it is recycled, so it issues the warning.

I would hesitate to call this a bug (or "flaw") in the linter, but it does mean that the warning can be ignored in this case.

来源：https://stackoverflow.com/questions/57225133/kotlin-also-function-strange-warning-in-android-studio