[android] Get all child views inside LinearLayout at once

((ViewGroup) findViewById(android.R.id.content));// you can use this in an Activity to get your layout root view, then pass it to findAllEdittexts() method below.

Here I am iterating only EdiTexts, if you want all Views you can replace EditText with View.

SparseArray<EditText> array = new SparseArray<EditText>();

private void findAllEdittexts(ViewGroup viewGroup) {

    int count = viewGroup.getChildCount();
    for (int i = 0; i < count; i++) {
        View view = viewGroup.getChildAt(i);
        if (view instanceof ViewGroup)
            findAllEdittexts((ViewGroup) view);
        else if (view instanceof EditText) {
            EditText edittext = (EditText) view;
            array.put(editText.getId(), editText);
        }
    }
}