自定義RadioGroup，實現單選功能

擴展RadioGroup，實現RadioButton換行可單選功能；

1、效果圖：

2、自定義MyRadioGroup

/**
 * @Dec ：解決RadioGroup中兩個RadioButton選中以及RadioButton換行佈局的RadioGroup
 * <p>
 * https://blog.csdn.net/yuanzihui/article/details/50462496
 * @Author : Caowj
 * @Date : 2018/11/20 16:48
 */
public class MyRadioGroup 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;

    public MyRadioGroup(Context context) {
        super(context);
        setOrientation(VERTICAL);
        init();
    }

    public MyRadioGroup(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);
    }

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

            ((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(MyRadioGroup.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;

                    ((RadioButton) button).setOnTouchListener(new OnTouchListener() {

                        @Override
                        public boolean onTouch(View v, MotionEvent event) {
//                            LegoLog.d("onCheckedChanged...");
                            ((RadioButton) button).setChecked(true);
                            checkRadioButton((RadioButton) button);
                            if (mOnCheckedChangeListener != null) {
                                mOnCheckedChangeListener.onCheckedChanged(MyRadioGroup.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 {
                            ((RadioButton) button).setChecked(false);
                        }
                    }
                }
            }
        }
    }

    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);
        }
    }

    public int getCheckedRadioButtonId() {
        return mCheckedId;
    }

    public void clearCheck() {
        check(-1);
    }

    public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
        mOnCheckedChangeListener = listener;
    }

    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new MyRadioGroup.LayoutParams(getContext(), attrs);
    }

    @Override
    protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
        return p instanceof MyRadioGroup.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(MyRadioGroup.class.getName());
    }

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

    public interface OnCheckedChangeListener {
        public void onCheckedChanged(MyRadioGroup group, int checkedId);
    }

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

        public LayoutParams(int w, int h) {
            super(w, h);
        }

        public LayoutParams(int w, int h, float initWeight) {
            super(w, h, initWeight);
        }

        public LayoutParams(ViewGroup.LayoutParams p) {
            super(p);
        }

        public LayoutParams(MarginLayoutParams source) {
            super(source);
        }

        @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;
            }
        }
    }

    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);
        }
    }

    private class PassThroughHierarchyChangeListener implements
            OnHierarchyChangeListener {
        private OnHierarchyChangeListener mOnHierarchyChangeListener;

        public void onChildViewAdded(View parent, View child) {
            if (parent == MyRadioGroup.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);
            }
        }

        public void onChildViewRemoved(View parent, View child) {
            if (parent == MyRadioGroup.this && child instanceof RadioButton) {
                ((RadioButton) child).setOnCheckedChangeListener(null);
            }

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

3、佈局文件

1、xml文件

<com.kedacom.androidteam.trafficpoliceaffairs.widget.MyRadioGroup
     android:id="@+id/rg_color_option"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:layout_marginTop="18dp"
     android:orientation="vertical">

     <LinearLayout
         android:id="@+id/top_layout"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:gravity="center"
         android:orientation="horizontal">

         <RadioButton
             android:id="@+id/rb_item_blue"
             style="@style/radio_button_car_style"
             android:layout_marginEnd="3dp"
             android:background="@drawable/card_num_bg_blue"
             android:tag="blue"
             android:textColor="@color/car_white" />

         <RadioButton
             android:id="@+id/rb_item_white"
             style="@style/radio_button_car_style"
             android:layout_marginEnd="3dp"
             android:background="@drawable/card_num_bg_grey"
             android:tag="white"
             android:textColor="@color/car_black" />

         <RadioButton
             android:id="@+id/rb_item_green"
             style="@style/radio_button_car_style"
             android:layout_marginEnd="3dp"
             android:background="@drawable/card_num_bg_green"
             android:tag="green"
             android:textColor="@color/car_black" />
     </LinearLayout>

     <LinearLayout
         android:id="@+id/bottom_layout"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginTop="10dp"
         android:gravity="center"
         android:orientation="horizontal">

         <RadioButton
             android:id="@+id/rb_item_yellow"
             style="@style/radio_button_car_style"
             android:layout_marginEnd="3dp"
             android:background="@drawable/card_num_bg_yellow"
             android:tag="yellow"
             android:textColor="@color/car_black" />

         <RadioButton
             android:id="@+id/rb_item_black"
             style="@style/radio_button_car_style"
             android:layout_marginEnd="3dp"
             android:background="@drawable/card_num_bg_black"
             android:tag="black"
             android:textColor="@color/car_white" />

         <RadioButton
             android:id="@+id/rb_item_other"
             style="@style/radio_button_car_style"
             android:layout_marginEnd="3dp"
             android:background="@drawable/card_num_bg_purple"
             android:tag="other"
             android:text="其他顏色"
             android:textColor="@color/car_other_txt" />
     </LinearLayout>
 </com.kedacom.androidteam.trafficpoliceaffairs.widget.MyRadioGroup>

2、自定義的RadioButton樣式：card_num_bg_blue.xml

<!--車牌：黑底白字-->
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/icon_plate_color_blue_selected" android:state_checked="true" />
    <item android:drawable="@drawable/icon_plate_color_blue" android:state_checked="false" />
</selector>

同理定義其他樣式。

4、具體使用

1、設置默認選中：
 //默認選中藍色車牌
 rg_color_option.check(R.id.rb_item_blue)

2、監聽選擇的結果
rg_color_option.setOnCheckedChangeListener { group, checkedId ->
    val radioButton: RadioButton? = findViewById(checkedId)
    val tag: String = radioButton?.tag.toString()
    nViewModel.plateColor = tag
    // TODO 弊端：會回調多次
    LegoLog.d("tag->$tag")
}