android - Android Fragments：如何循环通过片段控件

Question

如何使我的 Fragment 中的所有 Spinner 都可聚焦？

在我的布局的 XML 中设置android:focusableInTouchMode和android:focusable没有效果。

更一般地说，我在遍历 Fragment 的控件并查找特定类型的所有控件（例如所有 Spinners 或所有 EditTexts）时遇到了麻烦。

Answer 1

这对我来说非常棘手，所以我想我会在这里发布我的解决方案。这解决了一个特定问题（如何使微调器可聚焦），但也解决了一个更普遍的问题（如何循环通过片段中的控件。

public class MyFragment extends Fragment {

    private static ArrayList<Spinner> spinners = new ArrayList<Spinner>();


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        // inflate the layout
        View layout = inflater.inflate(R.layout.my_fragment_xml, container, false);

        // cast our newly inflated layout to a ViewGroup so we can 
        // enable looping through its children
        set_spinners((ViewGroup)layout);

        // now we can make them focusable
        make_spinners_focusable();

        return layout;
    }

    //find all spinners and add them to our static array

    private void set_spinners(ViewGroup container) {
        int count = container.getChildCount();
        for (int i = 0; i < count; i++) {
            View v = container.getChildAt(i);
            if (v instanceof Spinner) {
                spinners.add((Spinner) v);
            } else if (v instanceof ViewGroup) {
                //recurse through children
                set_spinners((ViewGroup) v);
            }
        }
    }

    //make all spinners in this fragment focusable
    //we are forced to do this in code

    private void make_spinners_focusable() {            
        for (Spinner s : spinners) {
            s.setFocusable(true);
            s.setFocusableInTouchMode(true);
            s.setOnFocusChangeListener(new View.OnFocusChangeListener() {
                @Override
                public void onFocusChange(View v, boolean hasFocus) {
                    if (hasFocus) {
                        v.performClick();
                    }
                }
            });
        }
    }


}

Answer 2

如果活动中有嵌套布局，则选择的答案set_spinners()不起作用。getChildCount()只给第一级的孩子。最好getAllChildrenBFS从这个答案中使用：

private List<View> getAllChildrenBFS(View v) {
    List<View> visited = new ArrayList<View>();
    List<View> unvisited = new ArrayList<View>();
    unvisited.add(v);

    while (!unvisited.isEmpty()) {
        View child = unvisited.remove(0);
        visited.add(child);
        if (!(child instanceof ViewGroup)) continue;
        ViewGroup group = (ViewGroup) child;
        final int childCount = group.getChildCount();
        for (int i=0; i<childCount; i++) unvisited.add(group.getChildAt(i));
    }

    return visited;
}