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？