Activity has leaked window that was originally added

Question

What is this error, and why does it happen?

05-17 18:24:57.069: ERROR/WindowManager(18850): Activity com.mypkg.myP has leaked window com.android.internal.pol         


        

Answer 1

here is a solution when you do want to dismiss AlertDialog but do not want to keep a reference to it inside activity.

solution requires you to have androidx.lifecycle dependency in your project (i believe at the moment of the comment it's a common requirement)

this lets you to delegate dialog's dismiss to external object (observer), and you dont need to care about it anymore, because it's auto-unsubscribed when activity dies. (here is proof: https://github.com/googlecodelabs/android-lifecycles/issues/5).

so, the observer keeps the reference to dialog, and activity keeps reference to observer. when "onPause" happens - observer dismisses the dialog, and when "onDestroy" happens - activity removes observer, so no leak happens (well, at least i dont see error in logcat anymore)

// observer
class DialogDismissLifecycleObserver( private var dialog: AlertDialog? ) : LifecycleObserver {
    @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
    fun onPause() {
        dialog?.dismiss()
        dialog = null
    }
}
// activity code
private fun showDialog() {
        if( isDestroyed || isFinishing ) return
        val dialog = AlertDialog
            .Builder(this, R.style.DialogTheme)
            // dialog setup skipped
            .create()
        lifecycle.addObserver( DialogDismissLifecycleObserver( dialog ) )
        dialog.show()
}