The code snippet below is from my onOptionsItemSelected function. Lines 2-5 below are suppose to hide the soft keyboard if it is showing OR call the activity's finish function otherwise.
I got this piece of code from one of the answers to 'How to Hide a SoftKeyboard' on stack overflow. It works fine on my phone but when I recently submitted my app for internal testing on playstore, I found out that it is throwing NPE sometimes. Can someone explain the logic behind why this might be happening please?
R.id.done -> {
val view:View? = this.currentFocus!! // throws null pointer exception
val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
if (bool && view!=null) {
imm.hideSoftInputFromWindow(view.windowToken, 0)
} else{
finish()
}
return true
The point of the !! operator is to convert a value of nullable type to the non-nullable equivalent while actively ensuring that the value is indeed not null (and throwing an NPE otherwise).
Here is what your code is actually doing:
val nonNullView: View = this.currentFocus!! // crashes if null
val view: View? = nonNullView
As you can see, !! has to throw an exception if the value is null, because a null value cannot be of type View (non nullable).
In your case, you end up with a nullable type View? anyway, so you don't need the extra temporary restriction imposed by !!, so you may as well just remove it:
val view: View? = this.currentFocus