android: 分享一个带多行选择功能的RadioGroup
分享一个带多行选择功能的RadioGroup, Github上看到的。
android 的RadioGroup有两个缺陷:
1. 不支持多行选择
什么意思呢?比如要实现下图这样的效果:
上面的10组选项其实都只能单选,但是要用RadioGroup去做的话,最少要定义3个RadioGroup, 原生的RadioGroup只支持单向排列,要么是横向,要么是纵向, 且不能自动换行。
2. 没办法自动区分选中状态是由代码触发的还是用户触发的
这个问题其实也存在于SwitchButton、CheckBox等其它原生控件中。这点我觉得非常不好,因为这个需求其实很常见,比如我进入一个新界面,需要更新RadioGroup中RadioButton的选中状态,如果你直接使用RadioGroup#check()或RadioButton#setChecked()方法,这两个方法都会触发监听器的 onCheckedChanged() 回调,而我们一般是将选中后执行的动作写在这个回调方法里的,这样就会导致一个很奇葩的现象:比如选中按钮后需要下一个setter指令,我更新界面时调用了RadioButton#setChecked()方法,本来是来更新界面的,结果却莫名其妙下了一个setter指令。
另外,使用RadioGroup#check()方法还会触发多次 onCheckedChanged() 回调!这是最坑的,完全跟我们的预期效果不一样,你可以说是我们用法上的问题,但我觉得一个好的api设计最起码从名称上就让人一目了然,光看名字就知道能达到什么效果, 而不是用了发现跟预期不一致,睬了个坑,再回去翻源码,发现原来是这样设计的,关于这个问题可参考:Android-为什么 RadioGroup.onCheckedChanged() 会调用多次?
下面直接贴代码:
我在上面加了一段code, 用于在代码选中时不会触发 onCheckedChanged()方法。 setCheckWithoutNotif
/** * RadioGroup with multi-line function and Code selection function * <br/> */ 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; } /** * Use program to check a radioButton, the {@link OnCheckedChangeListener#onCheckedChanged(MultiLineRadioGroup, int)} * method will not be triggered * * @param rationButtonId Selected radio button ID. * @param checked Checked state. */ public void setChecked(int rationButtonId, boolean checked) { RadioButton radioButton = findViewById(rationButtonId); if (radioButton != null) { OnCheckedChangeListener tmpListener = mOnCheckedChangeListener; setOnCheckedChangeListener(null); radioButton.setChecked(checked); setOnCheckedChangeListener(tmpListener); } } /** * <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> */ 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); } } } }
使用这份code, 可以很轻易实现多行的RadioButton效果,另外如果想选中RadioButton时不触发 onCheckedChanged 回调,可以调用: public void setChecked(int rationButtonId, boolean checked) 方法,其实这个code的原始作者也加了这个功能,
setCheckWithoutNotif , 但我最开始没看到,所以就自己实现了一份,也可以实现相同的效果。
参考链接:
1. Android-为什么 RadioGroup.onCheckedChanged() 会调用多次?