[英]How to get same childfragments(having recyclerview) instance in all the fragments of viewpager?
[英]ViewPager fragments are all referencing the same RecyclerView and/or Adapter
我有一个片段,其中包含一个RecyclerView来显示给定日期的事件。 我正在使用ViewPager将片段分成多天; 星期六活动的片段和星期日活动的片段。
但是,似乎两个片段都引用相同的RecyclerView和/或适配器,因为这只是显示事件的最后一个选项卡(在本例中为Sunday)。
在我的特定情况下,星期六有两个事件,而星期日没有任何事件。 两个片段都有空的RecyclerViews。 为了确认我的理论是由最后一个选项卡引起的,我更改了日期。 这导致两个RecyclerViews都发生两个事件(星期六起)。
以下是各个片段的相关代码:
public class EventListFragment extends Fragment{
private EventAdapter mEventAdapter;
private static final String DATE_ARG = "eventDate";
public static EventListFragment newInstance(LocalDate date){
EventListFragment eventListFragment = new EventListFragment();
Bundle args = new Bundle();
args.putSerializable(DATE_ARG, date);
eventListFragment.setArguments(args);
return eventListFragment;
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_event_list, container, false);
// Setup recyclerview
RecyclerView eventRecyclerView = (RecyclerView) view.findViewById(R.id.event_recycler_view);
LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
eventRecyclerView.setLayoutManager(layoutManager);
// Get date
LocalDate eventDate = (LocalDate) getArguments().getSerializable(DATE_ARG);
// Set adapter
mEventAdapter = new EventAdapter(getActivity(), getEvents(eventDate));
eventRecyclerView.setAdapter(mEventAdapter);
return view;
}
}
getEvents()
只是一个私有函数,用于返回给定日期的事件。 我已经使用调试器以及单元测试来验证它是否可以正常工作。 调试器显示它为每个Fragment提取了正确的列表,但是正如我所解释的,它们无法正确显示。
这是父片段的相关代码:
public class EventFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_event, container, false);
// Get and set up viewpager
final ViewPager viewPager = (ViewPager) view.findViewById(R.id.event_view_pager);
EventFragmentAdapter eventFragmentAdapter = new EventFragmentAdapter(getFragmentManager(), getEventDates());
viewPager.setAdapter(eventFragmentAdapter);
// Get and set up tablayout
final TabLayout tabLayout = (TabLayout) view.findViewById(R.id.event_tabs);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
tabLayout.post(new Runnable() {
@Override
public void run() {
tabLayout.setupWithViewPager(viewPager);
}
});
return view;
}
}
与最后一个类似, getEventDates()
只是提取事件发生的日期。 目前出于测试目的,由于我们尚未设置数据库,因此我正在对返回的日期列表进行硬编码。 我取消此方法是因为我希望该应用程序能够在2016年再次运行,而日期可能有所不同:
private List<LocalDate> getEventDates(){
List<LocalDate> eventDates = new ArrayList<>();
eventDates.add(new LocalDate(2015, 10, 17));
eventDates.add(new LocalDate(2015, 10, 18));
return eventDates;
}
相关代码的最后一部分是我正在为ViewPager使用的FragmentStatePagerAdapter:
public class EventFragmentAdapter extends FragmentStatePagerAdapter {
private List<LocalDate> mEventDates;
public EventFragmentAdapter(FragmentManager fragmentManager, List<LocalDate> eventDates){
super(fragmentManager);
this.mEventDates = eventDates;
}
@Override
public Fragment getItem(int i) {
return EventListFragment.newInstance(mEventDates.get(i));
}
@Override
public int getCount() {
return mEventDates.size();
}
@Override
public CharSequence getPageTitle(int position) {
return mEventDates.get(position).dayOfWeek().getAsText();
}
}
为什么两个列表总是相同并且基于ViewPager的最后一个选项卡的想法? 我假设他们以某种方式引用了相同的RecyclerView或相同的RecyclerViewAdapter,但是我没有针对这些的任何静态字段,因此我不确定它是如何发生的。
一个漫长的寻找和一种反气候的解决方案(与大多数困难的bug一样)。 由于该错误不在上面的代码中,因此也有点不公平,我不得不寻找您的git项目来解决它。 该错误在EventAdapter
:
public class EventAdapter extends RecyclerView.Adapter<EventAdapter.ViewHolder> {
private static final List<Event> mEvents;
private final Context mContext;
public EventAdapter(Context context, List<Event> events){
this.mContext = context;
mEvents = events;
}
...
}
mEvents
是静态的!...因此它在mEvents
所有实例之间mEvents
。 这可以完美地解释该错误,因为最后一次更新将为所有EventAdapters
设置值。
看起来您mEvents
静态,以便可以在ViewHolders
访问它。 相反,您可以仅将单个事件存储在ViewHolder
然后删除危险的static修饰符。 另一方面,为开源项目万岁!
我已经看过您的代码,并且完全同意Travor的观点-您使用的是静态成员,每次创建新的Adapter时该成员都会被替换(因此它仅获取最后的页面数据)。 为了使它正常工作,我对您的项目做了一些修改。 看一看,希望它会有用。
EventFragment:将getFragmentManager替换为getChildFragmentManager,因为您需要EventListFragment由EventFragment片段管理器而不是活动片段管理器处理
public class EventFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_event, container, false);
// Get and set up viewpager
final ViewPager viewPager = (ViewPager) view.findViewById(R.id.event_view_pager);
EventFragmentAdapter eventFragmentAdapter = new EventFragmentAdapter(getChildFragmentManager(), getEventDates());
viewPager.setAdapter(eventFragmentAdapter);
// Get and set up tablayout
final TabLayout tabLayout = (TabLayout) view.findViewById(R.id.event_tabs);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
tabLayout.post(new Runnable() {
@Override
public void run() {
tabLayout.setupWithViewPager(viewPager);
}
});
return view;
}
/**
* Retrieves the event dates for the hackathon so that the proper events can be displayed.
* @return
*/
private List<LocalDate> getEventDates(){
List<LocalDate> eventDates = new ArrayList<>();
eventDates.add(new LocalDate(2015, 10, 17));
eventDates.add(new LocalDate(2015, 10, 18));
return eventDates;
}
}
EventListFragment-我修改了查询,因为sqlite查询不适用于我的语言环境(意大利语)
public class EventListFragment extends Fragment{
private EventAdapter mEventAdapter;
private static final String TAG = EventListFragment.class.getSimpleName();
private static final String DATE_ARG = "eventDate";
public static EventListFragment newInstance(LocalDate date){
EventListFragment eventListFragment = new EventListFragment();
Bundle args = new Bundle();
args.putSerializable(DATE_ARG, date);
eventListFragment.setArguments(args);
return eventListFragment;
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_event_list, container, false);
// Setup recyclerview
RecyclerView eventRecyclerView = (RecyclerView) view.findViewById(R.id.event_recycler_view);
LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
eventRecyclerView.setLayoutManager(layoutManager);
// Get date
LocalDate eventDate = (LocalDate) getArguments().getSerializable(DATE_ARG);
// Set adapter
mEventAdapter = new EventAdapter(getEvents(eventDate));
eventRecyclerView.setAdapter(mEventAdapter);
Log.v(TAG, eventRecyclerView.toString());
return view;
}
/**
* Retrieves the events for the given date for the fragment.
*/
private List<Event> getEvents(LocalDate date){
List<Event> returnList = new ArrayList<>();
String dateString = Utility.getDBDateString(date);
List<String> dateList = new ArrayList<>();
Cursor cursor = getActivity().getContentResolver().query(
GHContract.EventEntry.CONTENT_URI,
new String[]{ "*", "substr(" + GHContract.EventEntry.COLUMN_TIME + ",0,11)" },
"substr(" + GHContract.EventEntry.COLUMN_TIME + ",0,11) = ? ",
new String[]{dateString},
GHContract.EventEntry.COLUMN_TIME
);
while(cursor.moveToNext()){
returnList.add(new Event(cursor));
dateList.add(cursor.getString(cursor.getColumnIndex(GHContract.EventEntry.COLUMN_TIME)));
}
cursor.close();
return returnList;
}
}
EventAdapter-删除了static关键字和对活动上下文的引用(您需要将上下文获得其他位置)
public class EventAdapter extends RecyclerView.Adapter<EventAdapter.ViewHolder> {
private List<Event> mEvents;
public EventAdapter(List<Event> events){
mEvents = events;
}
/**
* Inflates the view for Event items.
*/
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_event, parent, false);
return new ViewHolder(view);
}
/**
* Binds the data for an event to its view.
*/
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Event event = mEvents.get(position);
holder.timeView.setText(Utility.getTimeString(event.getTime()));
holder.titleView.setText(event.getTitle());
holder.locationView.setText(event.getLocation());
// If reminder time is not null, show check mark. If it is, show plus.
if(event.getReminderTime() != null){
holder.alarmView.setImageDrawable(holder.itemView.getResources().getDrawable(R.drawable.ic_alarm_on));
} else{
holder.alarmView.setImageDrawable(holder.itemView.getResources().getDrawable(R.drawable.ic_add_alarm));
}
}
/**
* Returns the size of the adapter.
*/
@Override
public int getItemCount() {
return mEvents.size();
}
/**
* Retains a reference to the view so `findViewById` calls are only made once for the adapter.
*/
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
public final TextView timeView;
public final TextView titleView;
public final TextView locationView;
public final ImageView alarmView;
public ViewHolder(View view){
super(view);
timeView = (TextView) view.findViewById(R.id.event_time);
titleView = (TextView) view.findViewById(R.id.event_title);
locationView = (TextView) view.findViewById(R.id.event_location);
alarmView = (ImageView) view.findViewById(R.id.event_add_reminder);
alarmView.setOnClickListener(this);
}
/**
* Handles the click a user makes on the alarm image view.
*/
@Override
public void onClick(View v) {
OnEventReminderClickListener activity = (OnEventReminderClickListener) v.getContext();
activity.onEventReminderClicked(mEvents.get(getPosition()));
}
}
/**
* Interface to call back to the activity when an alarm is clicked for an event item.
*/
public interface OnEventReminderClickListener{
void onEventReminderClicked(Event event);
}
}
最后是app / build.gradle,因为您需要为所有支持库(回收站,存储卡等)获得相同的版本
apply plugin: 'com.android.application'
android {
compileSdkVersion 22
buildToolsVersion "22.0.1"
defaultConfig {
applicationId "com.adammcneilly.grizzhacks"
minSdkVersion 15
targetSdkVersion 22
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:22.2.1'
compile 'joda-time:joda-time:2.7'
compile 'com.android.support:recyclerview-v7:22.2.1'
compile 'com.android.support:cardview-v7:22.2.1'
compile 'com.android.support:design:22.2.1'
}
你可以试试这个吗?
public class EventFragmentAdapter extends FragmentStatePagerAdapter {
private List<LocalDate> mEventDates;
private List<EventListFragment> mFragments;
public EventFragmentAdapter(FragmentManager fragmentManager, List<LocalDate> eventDates){
super(fragmentManager);
this.mEventDates = eventDates;
this.mFragments = new ArrayList<>;
for (LocalDate date : this.mEventDates) {
this.mFragments.add(EventListFragment.newInstance(date));
}
}
@Override
public Fragment getItem(int i) {
return mFragments.get(i);
}
@Override
public int getCount() {
return mEventDates.size();
}
@Override
public CharSequence getPageTitle(int position) {
return mEventDates.get(position).dayOfWeek().getAsText();
}
}
然后,您检查mFragent的每个项目是否具有预期的内容。
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