Call removeView() on the child's parent first

user_473831 0
Viewed 198959

First a little background:

I have a layout inside a scrollview. At first, when the user scrolls on the screen, the scrollview scrolls. However, after a certain amount of scroll, I was to disable the scroll on the scroll view the move the "scroll focus" onto a webview inside the child layout. This way, the scrollview sticks and all the scroll events go to the webview inside it.

So, for a solution, when the scroll threshold is reached, I remove the child layout from the scrollview and put it in scrollview's parent.(And make the scrollview invisible).

// Remove the child view from the scroll view
scrollView.removeView(scrollChildLayout);

// Get scroll view out of the way
scrollView.setVisibility(View.GONE);

// Put the child view into scrollview's parent view
parentLayout.addView(scrollChildLayout);

General Idea: (-> means contains)

Before: parentlayout -> scrollview -> scrollChildLayout

After : parentLayout -> scrollChildLayout

The above code is giving me this exception:

java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
           at android.view.ViewGroup.addViewInner(ViewGroup.java:1976)
           at android.view.ViewGroup.addView(ViewGroup.java:1871)
           at android.view.ViewGroup.addView(ViewGroup.java:1828)
           at android.view.ViewGroup.addView(ViewGroup.java:1808)

Do you know what's going on? I am clearly calling removeView on the parent.

scrollview android
11 Answers

Kotlin Solution

Kotlin simplifies parent casting with as?, returning null if left side is null or cast fails.

(childView.parent as? ViewGroup)?.removeView(childView)

Kotlin Extension Solution

If you want to simplify this even further, you can add this extension.

childView.removeSelf()

fun View?.removeSelf() {
    this ?: return
    val parentView = parent as? ViewGroup ?: return
    parentView.removeView(this)
}

It will safely do nothing if this View is null, parent view is null, or parent view is not a ViewGroup

NOTE: If you also want safe removal of child views by parent, add this:

fun ViewGroup.removeViewSafe(toRemove: View) {
    if (contains(toRemove)) removeView(toRemove)
}
user_9740450
Related