CODEWITHSUNDEEP
androidandroid-view
Laurent Meyer
Laurent Meyer

Reputation: 2881

Exploring the view tree in Android

It's maybe a bit abstract but I'd like to know if some of you have a decent solution to that problem:

I have a complicated layout and I need to find ALL the instances of a certain type of view.

I have few solutions but I find none of them perfect and I'd like to know if there is another way or a way to improve them.

MY FIRST OPTION

We can iterate in the view tree with getChildCount() and getChildAt() and then check with instanceof like in lots of SO answers.

for (int i = 0; i<parentContainer.getChildCount(); i++){
    View child = getChildAt(i);
    if (child instanceof BlaBla){
        // Do something wonderful
    }
}

It is highly inefficient because I have these instances in many places and in particular in nested places so I need to make this method recursive.

MY SECOND OPTION

It would be to work with dynamic tags or ids and use findViewById or findViewWithTag. But the issue is that it makes something more to configure and as always it makes the software more complicated.

So my question is: how can I do a complete search in the view tree in order to find all instances of a component without doing the search myself (because it would be probably be very inefficient)? Is that somehow possible?

Upvotes: 1

Views: 3134

Answers (1)

Ivan
Ivan

Reputation: 1526

So, I'm not sure second option is possible as in this case you'll need to create this views in runtime and assign some generated ID with some bit mask to recognize them later. If to create your views from layout you will end up with traversing tree view and assigning these special IDs which is pretty much accends to 1st option.

In my project I also have to dynamically apply colors to some views and I do it without recursion. Pattern is following:

ArrayList<View> views = new ArrayList<>();
views.add(getWindow().getDecorView());

    do {
      View v = views.remove(0);
       if (v instanceof ViewGroup) {
           ViewGroup group = (ViewGroup) v;
           for (int i = 0; i < group.getChildCount(); i++) {
             views.add(group.getChildAt(i));
           }
       }
       if (v instanceof MyCustomView) {
         //do whatever you need here
       }
    } while(!views.isEmpty());

So you get rid of using recursion and replace it with own stack and iteration through it. This solution quite efficient especially if you can skip things like ListView, RecyclerView.

Upvotes: 2

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