RadioGroup多行显示

今天做一个单选框，效果如下：

使用原始的RadioGroup可以实现布局，但因为把6个单选分为两个LinearLayout，导致无法互斥，Google官方的做法是写两个RadioGroup，但是要动态监听，感觉好麻烦，最理想的办法是自定义一个RadioGroup，一劳永逸。

原文地址：https://github.com/pheng/android_radiogroup_MutilRadioGroup

一个类足以，的确很牛逼，原理应该是拿所有嵌套布局里的RadioButton，然后动态重新组了一遍，既保证布局，又实现互斥。

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Build;
import android.util.AttributeSet;
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;

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

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

    /**
     * {@inheritDoc}
     */
    public MultiLineRadioGroup(Context context, AttributeSet attrs) {
        super(context, attrs);
        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;
    }

    /**
     * set the default checked radio button, without notification the listeners
     */
    public void setCheckWithoutNotif(int id) {
        if (id != -1 && (id == mCheckedId)) {
            return;
        }

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

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

        mCheckedId = id;
        mProtectFromCheckedChange = false;
    }

    @Override
    public void addView(View child, int index, ViewGroup.LayoutParams params) {
        List<RadioButton> btns = getAllRadioButton(child);
        if (btns != null && btns.size() > 0) {
            for (RadioButton button : btns) {
                if (button.isChecked()) {
                    mProtectFromCheckedChange = true;
                    if (mCheckedId != -1) {
                        setCheckedStateForView(mCheckedId, false);
                    }
                    mProtectFromCheckedChange = false;
                    setCheckedId(button.getId());
                }
            }
        }
        super.addView(child, index, params);
    }

    /**
     * get all radio buttons which are in the view
     *
     * @param child
     */
    private List<RadioButton> getAllRadioButton(View child) {
        List<RadioButton> btns = new ArrayList<RadioButton>();
        if (child instanceof RadioButton) {
            btns.add((RadioButton) child);
        } else if (child instanceof ViewGroup) {
            int counts = ((ViewGroup) child).getChildCount();
            for (int i = 0; i < counts; i++) {
                btns.addAll(getAllRadioButton(((ViewGroup) child).getChildAt(i)));
            }
        }
        return btns;
    }

    /**
     * <p>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()}.</p>
     *
     * @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;
        if (mOnCheckedChangeListener != null) {
            mOnCheckedChangeListener.onCheckedChanged(this, mCheckedId);
        }
    }

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

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

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

    /**
     * <p>Register a callback to be invoked when the checked radio button
     * changes in this group.</p>
     *
     * @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 MultiLineRadioGroup.LayoutParams(getContext(), attrs);
    }

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

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

    /**
     * <p>This set of layout parameters defaults the width and the height of
     * the children to {@link #WRAP_CONTENT} when they are not specified in the
     * XML file. Otherwise, this class ussed the value read from the XML file.</p>
     * <p/>
     * <p>See
     * for a list of all child view attributes that this class supports.</p>
     */
    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);
        }

        /**
         * <p>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.</p>
         *
         * @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;
            }
        }
    }

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

    /**
     * <p>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.</p>
     */
    private class PassThroughHierarchyChangeListener implements
            ViewGroup.OnHierarchyChangeListener {
        private ViewGroup.OnHierarchyChangeListener mOnHierarchyChangeListener;

        /**
         * {@inheritDoc}
         */
        @SuppressLint("NewApi")
        public void onChildViewAdded(View parent, View child) {
            if (parent == MultiLineRadioGroup.this) {
                List<RadioButton> btns = getAllRadioButton(child);
                if (btns != null && btns.size() > 0) {
                    for (RadioButton btn : btns) {
                        int id = btn.getId();
                        // generates an id if it's missing
                        if (id == View.NO_ID && Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
                            id = View.generateViewId();
                            btn.setId(id);
                        }
                        btn.setOnCheckedChangeListener(
                                mChildOnCheckedChangeListener);
                    }
                }
            }

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

        /**
         * {@inheritDoc}
         */
        public void onChildViewRemoved(View parent, View child) {
            if (parent == MultiLineRadioGroup.this) {
                List<RadioButton> btns = getAllRadioButton(child);
                if (btns != null && btns.size() > 0) {
                    for (RadioButton btn : btns) {
                        btn.setOnCheckedChangeListener(null);
                    }
                }
            }

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

然后调用即可：

<com.xuehu365.xuehu.utils.MultiLineRadioGroup
    android:id="@+id/type"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="5dp"
    android:background="@color/white"
    android:orientation="vertical"
    android:padding="10dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <RadioButton
            android:id="@+id/experienceProblem"
            style="@style/counsel_radio_button"
            android:text="体验问题" />

        <RadioButton
            android:id="@+id/userAdvice"
            style="@style/counsel_radio_button"
            android:text="功能建议" />

        <RadioButton
            android:id="@+id/contentSuggest"
            style="@style/counsel_radio_button"
            android:text="内容意见" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <RadioButton
            android:id="@+id/courseBuy"
            style="@style/counsel_radio_button"
            android:text="课程购买" />

        <RadioButton
            android:id="@+id/webProblem"
            style="@style/counsel_radio_button"
            android:text="网络问题" />

        <RadioButton
            android:id="@+id/other"
            style="@style/counsel_radio_button"
            android:text="其它" />
    </LinearLayout>
</com.xuehu365.xuehu.utils.MultiLineRadioGroup>