IllegalStateException异常:应用程序的PagerAdapter改变了适配器的内容,而无需调用PagerAdapter#notifyDataSetChanged [英] IllegalStateException: The application's PagerAdapter changed the adapter's content without calling PagerAdapter#notifyDataSetChanged
问题描述
我使用了 ViewPager
例如用动作条
从Android文档的>
不幸的是,当我叫 addTab
方法,但以下情况除外应用程序崩溃:
IllegalStateException异常:应用程序的PagerAdapter改 适配器的内容,而无需调用PagerAdapter#notifyDataSetChanged! 预计适配器项目数0,发现1。
这是 FragmentPagerAdapter
code:
公共静态类TabsAdapter扩展FragmentPagerAdapter
实现ActionBar.TabListener,ViewPager.OnPageChangeListener {
私人最终语境mContext;
私人最终动作条mActionBar;
私人最终ViewPager mViewPager;
私人最终的ArrayList< TabInfo> mTabs =新的ArrayList< TabInfo>();
静态final类TabInfo {
私人最终类别<> CLSS;
私人最终捆绑的args;
TabInfo(类<> _class,捆绑_args){
CLSS = _class;
的args = _args;
}
}
公共TabsAdapter(活动活动,ViewPager寻呼机){
超级(activity.getFragmentManager());
mContext =活动;
mActionBar = activity.getActionBar();
mViewPager =寻呼机;
mViewPager.setAdapter(本);
mViewPager.setOnPageChangeListener(本);
}
公共无效addTab(ActionBar.Tab选项卡,类<> CLSS,捆绑参数){
TabInfo信息=新TabInfo(CLSS,参数);
tab.setTag(信息);
tab.setTabListener(本);
mTabs.add(信息);
mActionBar.addTab(标签);
notifyDataSetChanged();
}
@覆盖
公众诠释getCount将(){
返回mTabs.size();
}
@覆盖
公共片段的getItem(INT位置){
TabInfo信息= mTabs.get(位置);
返回Fragment.instantiate(mContext,info.clss.getName(),info.args);
}
@覆盖
公共无效onPageScrolled(INT位置,浮positionOffset,诠释positionOffsetPixels){
}
@覆盖
公共无效onPageSelected(INT位置){
mActionBar.setSelectedNavigationItem(位置);
}
@覆盖
公共无效onPageScrollStateChanged(INT状态){
}
@覆盖
公共无效onTabSelected(TAB键,FragmentTransaction英尺){
对象标记= tab.getTag();
的for(int i = 0; I< mTabs.size();我++){
如果(mTabs.get(ⅰ)==标签){
mViewPager.setCurrentItem(ⅰ);
}
}
}
@覆盖
公共无效onTabUnselected(TAB键,FragmentTransaction英尺){
}
@覆盖
公共无效onTabReselected(TAB键,FragmentTransaction英尺){
}
}
}
我不会改变我的适配器在我的code的任何其他部分,我打电话从主线程的 addTab
法, addTab
方法结束通过调用 notifyDataSetChanged
。由于文档建议做:
PagerAdapter支持数据集的变化。数据集的改变必须发生在 主线程必须通过调用notifyDataSetChanged结束() 类似于从BaseAdapter衍生适配器视图适配器。
我有一个很难让我的 ViewPager
工作。最后,它似乎在文档中的例子是错误的。
在 addTab
方法应该如下:
公共无效addTab(TAB键,类<> CLSS,捆绑参数){
TabInfo信息=新TabInfo(CLSS,参数);
tab.setTag(信息);
tab.setTabListener(本);
mTabs.add(信息);
notifyDataSetChanged();
mActionBar.addTab(标签);
}
注意最后三个操作的顺序。在最初的例子, notifyDataSetChanged
的 mActionBar.addTab
函数之后被调用。
不幸的是,只要您拨打 addTab
在动作条
,添加的第一个选项卡中自动选择。正因为如此,在 onTabSelected
事件被触发,并尝试检索页面,它trhows的 IllegalStateException异常
,因为它注意到预期的项目数和实际一个之间的差异。
I'm using the ViewPager
example with ActionBar
tabs taken from the Android documentation here.
Unfortunately, as soon as I call the addTab
method, the application crashes with the following exception:
IllegalStateException: The application's PagerAdapter changed the adapter's content without calling PagerAdapter#notifyDataSetChanged! Expected adapter item count 0, found 1.
This is the FragmentPagerAdapter
code:
public static class TabsAdapter extends FragmentPagerAdapter
implements ActionBar.TabListener, ViewPager.OnPageChangeListener {
private final Context mContext;
private final ActionBar mActionBar;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
static final class TabInfo {
private final Class<?> clss;
private final Bundle args;
TabInfo(Class<?> _class, Bundle _args) {
clss = _class;
args = _args;
}
}
public TabsAdapter(Activity activity, ViewPager pager) {
super(activity.getFragmentManager());
mContext = activity;
mActionBar = activity.getActionBar();
mViewPager = pager;
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
}
public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {
TabInfo info = new TabInfo(clss, args);
tab.setTag(info);
tab.setTabListener(this);
mTabs.add(info);
mActionBar.addTab(tab);
notifyDataSetChanged();
}
@Override
public int getCount() {
return mTabs.size();
}
@Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
mActionBar.setSelectedNavigationItem(position);
}
@Override
public void onPageScrollStateChanged(int state) {
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
Object tag = tab.getTag();
for (int i=0; i<mTabs.size(); i++) {
if (mTabs.get(i) == tag) {
mViewPager.setCurrentItem(i);
}
}
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
}
}
I'm not modifying my adapter in any other part of my code and I'm calling the addTab
method from the main thread, the addTab
method ends with a call to notifyDataSetChanged
. As the documentation recommends to do:
PagerAdapter supports data set changes. Data set changes must occur on the main thread and must end with a call to notifyDataSetChanged() similar to AdapterView adapters derived from BaseAdapter.
I had an hard time making my ViewPager
working. At the end, it seems the example in the documentation is wrong.
The addTab
method should be as follows:
public void addTab(Tab tab, Class<?> clss, Bundle args) {
TabInfo info = new TabInfo(clss, args);
tab.setTag(info);
tab.setTabListener(this);
mTabs.add(info);
notifyDataSetChanged();
mActionBar.addTab(tab);
}
Notice the order of the last three operations. In the original example, notifyDataSetChanged
was called after the mActionBar.addTab
function.
Unfortunately, as soon as you call the addTab
on the ActionBar
, the first tab you add is automatically selected. Because of this, the onTabSelected
event is fired and while trying to retrieve the page, it trhows the IllegalStateException
because it notices a discrepancy between the expected item count and the actual one.
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