Loop through all subviews of an Android view?

Question

I’m working on a game for Android. To help implement it, my idea is to create a subclass of a view. I would then insert several instances of this class as children of the ma

Answer 1

I have made a small example of a recursive function:

public void recursiveLoopChildren(ViewGroup parent) {
        for (int i = 0; i < parent.getChildCount(); i++) {
            final View child = parent.getChildAt(i);
            if (child instanceof ViewGroup) {
                recursiveLoopChildren((ViewGroup) child);
                // DO SOMETHING WITH VIEWGROUP, AFTER CHILDREN HAS BEEN LOOPED
            } else {
                if (child != null) {
                    // DO SOMETHING WITH VIEW
                }
            }
        }
    }

The function will start looping over al view elements inside a ViewGroup (from first to last item), if a child is a ViewGroup then restart the function with that child to retrieve all nested views inside that child.

Answer 2

The alternative

public static void recursivelyFindChildren(View view) {
    if (view instanceof ViewGroup) {
        //ViewGroup
        ViewGroup viewGroup = (ViewGroup)view;

        for (int i = 0; i < viewGroup.getChildCount(); i++) {
            recursivelyFindChildren(viewGroup.getChildAt(i));
        }

    } else {
        //View
    }

}

Or you can return something you can use the next approach

@Nullable
private static WebView recursivelyFindWebView(View view) {
    if (view instanceof ViewGroup) {
        //ViewGroup
        ViewGroup viewGroup = (ViewGroup)view;

        if (!(viewGroup instanceof WebView)) {
            for (int i = 0; i < viewGroup.getChildCount(); i++) {
                WebView result = recursivelyFindWebView(viewGroup.getChildAt(i));

                if (result != null) {
                    return result;
                }
            }
        } else {
            //WebView

            WebView webView = (WebView)viewGroup;
            return webView;
        }

    }

    return null;
}

Answer 3

Using Views sounds like its going to be brutally difficult to render anything well if there is movement. You probably want to be drawing to a Canvas or using OpenGL unless you're doing something really static. Here's a great talk from last years I/O conference on making Android games. Its kind of long and you can skip about 15 minutes in. Also the source is available. That should give you a good idea of ways to go about things

Answer 4

@jqpubliq Is right but if you really want to go through all Views you can simply use the getChildCount() and getChildAt() methods from ViewGroup. A simple recursive method will do the rest.

Answer 5

Try this. Takes all views inside a parent layout & returns an array list of views.

public List<View> getAllViews(ViewGroup layout){
        List<View> views = new ArrayList<>();
        for(int i =0; i< layout.getChildCount(); i++){
            views.add(layout.getChildAt(i));
        }
        return views;
    }