DeepRadioGroup.java

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CompoundButton;
import android.widget.RadioButton;
import android.widget.RadioGroup;

import java.util.ArrayList;
import java.util.List;

/**
 * {@link RadioGroup} supporting mutual exclusion in all {@link RadioButton} in the layout tree.
 * For my friend Gryzor ;)
 */
class DeepRadioGroup extends RadioGroup {

    private List<RadioButton> radioButtons = new ArrayList<>();
    private OnCheckedChangeListener onCheckedChangeListener;
    private OnHierarchyChangeListener onHierarchyChangeListener;
    private CompoundButton.OnCheckedChangeListener radioButtonChangeListener;

    public DeepRadioGroup(Context context) {
        super(context);
        init();
    }

    public DeepRadioGroup(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        super.setOnHierarchyChangeListener(new HierarchyChangeListener(this));
        radioButtonChangeListener = new RadioButtonChangeListener(this);
    }

    private void addRadioButton(RadioButton button) {
        radioButtons.add(button);
        button.setOnCheckedChangeListener(radioButtonChangeListener);
    }

    private void removeRadioButton(RadioButton child) {
        radioButtons.remove(child);
    }

    @Override
    public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) {
        onHierarchyChangeListener = listener;
    }

    private void delegateOnChildViewAdded(View parent, View child) {
        if (onHierarchyChangeListener != null) {
            onHierarchyChangeListener.onChildViewAdded(parent, child);
        }
    }

    private void delegateOnChildViewRemoved(View parent, View child) {
        if (onHierarchyChangeListener != null) {
            onHierarchyChangeListener.onChildViewRemoved(parent, child);
        }
    }

    @Override
    public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
        super.setOnCheckedChangeListener(listener);
        this.onCheckedChangeListener = listener;
    }

    private void triggerMutualExclusion(CompoundButton checked) {
        super.setOnCheckedChangeListener(null);
        for (RadioButton button : radioButtons) {
            if (button != checked) {
                button.setChecked(false);
            }
        }
        super.setOnCheckedChangeListener(onCheckedChangeListener);
    }

    private static class RadioButtonChangeListener implements CompoundButton.OnCheckedChangeListener {

        private DeepRadioGroup group;

        private RadioButtonChangeListener(DeepRadioGroup group) {
            this.group = group;
        }

        @Override
        public void onCheckedChanged(CompoundButton button, boolean isChecked) {
            if (isChecked) {
                group.triggerMutualExclusion(button);
            }
        }

    }

    @SuppressWarnings("StatementWithEmptyBody")
    private static class HierarchyChangeListener implements OnHierarchyChangeListener {

        private DeepRadioGroup group;

        private HierarchyChangeListener(DeepRadioGroup group) {
            this.group = group;
        }

        @Override
        public void onChildViewAdded(View parent, View child) {
            if (child instanceof RadioGroup) {
                // ignore nested groups
            } else if (child instanceof RadioButton) {
                group.addRadioButton((RadioButton) child);
            } else if (child instanceof ViewGroup) {
                ViewGroup group = (ViewGroup) child;
                for (int i = 0; i < group.getChildCount(); i++) {
                    onChildViewAdded(child, group.getChildAt(i));
                }
            }
            group.delegateOnChildViewAdded(parent, child);
        }

        @Override
        public void onChildViewRemoved(View parent, View child) {
            if (child instanceof RadioGroup) {
                // ignore nested groups
            } else if (child instanceof RadioButton) {
                group.removeRadioButton((RadioButton) child);
            } else if (child instanceof ViewGroup) {
                ViewGroup group = (ViewGroup) child;
                for (int i = 0; i < group.getChildCount(); i++) {
                    onChildViewRemoved(child, group.getChildAt(i));
                }
            }
            group.delegateOnChildViewRemoved(parent, child);
        }

    }
}