import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.CompoundButton;
import android.widget.LinearLayout;
import android.widget.RadioButton;

public class RadioGroup extends LinearLayout {
 // holds the checked id; the selection is empty by default 
 private int mCheckedId = -1;
 // tracks children radio buttons checked state 
 private CompoundButton.OnCheckedChangeListener mChildOnCheckedChangeListener;
 // when true, mOnCheckedChangeListener discards events 
 private boolean mProtectFromCheckedChange = false;
 private OnCheckedChangeListener mOnCheckedChangeListener;
 private PassThroughHierarchyChangeListener mPassThroughListener;

 /**
  * {@inheritDoc}
  */
 public RadioGroup(Context context) {
  super(context);
  setOrientation(VERTICAL);
  init();
 }

 /**
  * {@inheritDoc}
  */
 public RadioGroup(Context context, AttributeSet attrs) {
  super(context, attrs);
  mCheckedId = View.NO_ID;

  final int index = VERTICAL;
  setOrientation(index);

  init();
 }

 private void init() {
  mChildOnCheckedChangeListener = new CheckedStateTracker();
  mPassThroughListener = new PassThroughHierarchyChangeListener();
  super.setOnHierarchyChangeListener(mPassThroughListener);
 }

 /**
  * {@inheritDoc}
  */
 @Override
 public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) {
  // the user listener is delegated to our pass-through listener 
  mPassThroughListener.mOnHierarchyChangeListener = listener;
 }

 /**
  * {@inheritDoc}
  */
 @Override
 protected void onFinishInflate() {
  super.onFinishInflate();

  // checks the appropriate radio button as requested in the XML file 
  if (mCheckedId != -1) {
   mProtectFromCheckedChange = true;
   setCheckedStateForView(mCheckedId, true);
   mProtectFromCheckedChange = false;
   setCheckedId(mCheckedId);
  }
 }

 @Override
 public void addView(final View child, int index, ViewGroup.LayoutParams params) {
  if (child instanceof RadioButton) {
   child.setOnTouchListener(new OnTouchListener() {

    @Override
    public boolean onTouch(View v, MotionEvent event) {
     ((RadioButton) child).setChecked(true);
     checkRadioButton((RadioButton) child);
     if (mOnCheckedChangeListener != null) {
      mOnCheckedChangeListener.onCheckedChanged(RadioGroup.this, child.getId());
     }
     return true;
    }
   });
  } else if (child instanceof LinearLayout) {
   int childCount = ((LinearLayout) child).getChildCount();
   for (int i = 0; i < childCount; i++) {
    View view = ((LinearLayout) child).getChildAt(i);
    if (view instanceof RadioButton) {
     final RadioButton button = (RadioButton) view;
     button.setOnTouchListener(new OnTouchListener() {

      @Override
      public boolean onTouch(View v, MotionEvent event) {
       button.setChecked(true);
       checkRadioButton(button);
       if (mOnCheckedChangeListener != null) {
        mOnCheckedChangeListener.onCheckedChanged(RadioGroup.this, button.getId());
       }
       return true;
      }
     });
    }
   }
  }
  super.addView(child, index, params);
 }

 private void checkRadioButton(RadioButton radioButton) {
  View child;
  int radioCount = getChildCount();
  for (int i = 0; i < radioCount; i++) {
   child = getChildAt(i);
   if (child instanceof RadioButton) {
    if (child == radioButton) {
     // do nothing 
    } else {
     ((RadioButton) child).setChecked(false);
    }
   } else if (child instanceof LinearLayout) {
    int childCount = ((LinearLayout) child).getChildCount();
    for (int j = 0; j < childCount; j++) {
     View view = ((LinearLayout) child).getChildAt(j);
     if (view instanceof RadioButton) {
      final RadioButton button = (RadioButton) view;
      if (button == radioButton) {
       // do nothing 
      } else {
       button.setChecked(false);
      }
     }
    }
   }
  }
 }

 /**
  * 
Sets the selection to the radio button whose identifier is passed in
  * parameter. Using -1 as the selection identifier clears the selection;
  * such an operation is equivalent to invoking {@link #clearCheck()}.
  *
  * @param id the unique id of the radio button to select in this group
  * @see #getCheckedRadioButtonId()
  * @see #clearCheck()
  */
 public void check(int id) {
  // don't even bother 
  if (id != -1 && (id == mCheckedId)) {
   return;
  }

  if (mCheckedId != -1) {
   setCheckedStateForView(mCheckedId, false);
  }

  if (id != -1) {
   setCheckedStateForView(id, true);
  }

  setCheckedId(id);
 }

 private void setCheckedId(int id) {
  mCheckedId = id;
 }

 private void setCheckedStateForView(int viewId, boolean checked) {
  View checkedView = findViewById(viewId);
  if (checkedView != null && checkedView instanceof RadioButton) {
   ((RadioButton) checkedView).setChecked(checked);
  }
 }

 /**
  * 
Returns the identifier of the selected radio button in this group.
  * Upon empty selection, the returned value is -1.
  *
  * @return the unique id of the selected radio button in this group
  * @attr ref android.R.styleable#RadioGroup_checkedButton
  * @see #check(int)
  * @see #clearCheck()
  */
 public int getCheckedRadioButtonId() {
  return mCheckedId;
 }

 /**
  * 
Clears the selection. When the selection is cleared, no radio button
  * in this group is selected and {@link #getCheckedRadioButtonId()} returns
  * null.
  *
  * @see #check(int)
  * @see #getCheckedRadioButtonId()
  */
 public void clearCheck() {
  check(-1);
 }

 /**
  * 
Register a callback to be invoked when the checked radio button
  * changes in this group.
  *
  * @param listener the callback to call on checked state change
  */
 public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
  mOnCheckedChangeListener = listener;
 }

 /**
  * {@inheritDoc}
  */
 @Override
 public LayoutParams generateLayoutParams(AttributeSet attrs) {
  return new RadioGroup.LayoutParams(getContext(), attrs);
 }

 /**
  * {@inheritDoc}
  */
 @Override
 protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
  return p instanceof RadioGroup.LayoutParams;
 }

 @Override
 protected LinearLayout.LayoutParams generateDefaultLayoutParams() {
  return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
 }

 @Override
 public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
  super.onInitializeAccessibilityEvent(event);
  event.setClassName(RadioGroup.class.getName());
 }

 @Override
 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
  super.onInitializeAccessibilityNodeInfo(info);
  info.setClassName(RadioGroup.class.getName());
 }

 public static class LayoutParams extends LinearLayout.LayoutParams {
  /**
   * {@inheritDoc}
   */
  public LayoutParams(Context c, AttributeSet attrs) {
   super(c, attrs);
  }

  /**
   * {@inheritDoc}
   */
  public LayoutParams(int w, int h) {
   super(w, h);
  }

  /**
   * {@inheritDoc}
   */
  public LayoutParams(int w, int h, float initWeight) {
   super(w, h, initWeight);
  }

  /**
   * {@inheritDoc}
   */
  public LayoutParams(ViewGroup.LayoutParams p) {
   super(p);
  }

  /**
   * {@inheritDoc}
   */
  public LayoutParams(MarginLayoutParams source) {
   super(source);
  }

  /**
   * 
Fixes the child's width to
   * {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT} and the child's
   * height to {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT}
   * when not specified in the XML file.
   *
   * @param a   the styled attributes set
   * @param widthAttr the width attribute to fetch
   * @param heightAttr the height attribute to fetch
   */
  @Override
  protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr) {
   if (a.hasValue(widthAttr)) {
    width = a.getLayoutDimension(widthAttr, "layout_width");
   } else {
    width = WRAP_CONTENT;
   }

   if (a.hasValue(heightAttr)) {
    height = a.getLayoutDimension(heightAttr, "layout_height");
   } else {
    height = WRAP_CONTENT;
   }
  }
 }

 /**
  * 
Interface definition for a callback to be invoked when the checked
  * radio button changed in this group.
  */
 public interface OnCheckedChangeListener {
  /**
   * 
Called when the checked radio button has changed. When the
   * selection is cleared, checkedId is -1.
   *
   * @param group  the group in which the checked radio button has changed
   * @param checkedId the unique identifier of the newly checked radio button
   */
  void onCheckedChanged(RadioGroup group, int checkedId);
 }

 private class CheckedStateTracker implements CompoundButton.OnCheckedChangeListener {
  public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
   // prevents from infinite recursion 
   if (mProtectFromCheckedChange) {
    return;
   }

   mProtectFromCheckedChange = true;
   if (mCheckedId != -1) {
    setCheckedStateForView(mCheckedId, false);
   }
   mProtectFromCheckedChange = false;

   int id = buttonView.getId();
   setCheckedId(id);
  }
 }

 /**
  * 
A pass-through listener acts upon the events and dispatches them
  * to another listener. This allows the table layout to set its own internal
  * hierarchy change listener without preventing the user to setup his.
  */
 private class PassThroughHierarchyChangeListener implements ViewGroup.OnHierarchyChangeListener {
  private ViewGroup.OnHierarchyChangeListener mOnHierarchyChangeListener;

  /**
   * {@inheritDoc}
   */
  public void onChildViewAdded(View parent, View child) {
   if (parent == RadioGroup.this && child instanceof RadioButton) {
    int id = child.getId();
    // generates an id if it's missing 
    if (id == View.NO_ID) {
     id = child.hashCode();
     child.setId(id);
    }
    ((RadioButton) child).setOnCheckedChangeListener(mChildOnCheckedChangeListener);
   }

   if (mOnHierarchyChangeListener != null) {
    mOnHierarchyChangeListener.onChildViewAdded(parent, child);
   }
  }

  /**
   * {@inheritDoc}
   */
  public void onChildViewRemoved(View parent, View child) {
   if (parent == RadioGroup.this && child instanceof RadioButton) {
    ((RadioButton) child).setOnCheckedChangeListener(null);
   }

   if (mOnHierarchyChangeListener != null) {
    mOnHierarchyChangeListener.onChildViewRemoved(parent, child);
   }
  }
 }
}