why kotlin by lazy can cause memory leak in android?

Question

I define a loading Dialog like this

private val loadingDialog: LoadingDialog by lazy { LoadingDialog() }

loadingDialog is a DialogFragment

when I use leakcanary to watch my app, I find the loadingDialog cause memory

Can somebody help me?

Answer 1

When you define a val delegated by lazy {...}, the lambda you pass to the delegate captures the scope into its closure (though it's only the outer this in your case, it may be an Activity instance).

Then the delegate instance holds the references it captured until the moment the val is first accessed. Then it invokes the lambda and 'forgets' the closure.

But if your val is accessed too late (or never), the lambda's closure may keep the objects in memory that would otherwise be disposed, which is a possible memory leak.