与getSupportFragmentManager时（findFragmentByTag（）的返回null） [英] findFragmentByTag() is returning null when working with getSupportFragmentManager()
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问题描述
我的支持库动作条的工作，因为我使用的是旧的最低SDK。在活动中，我使用FragmentTabHost因为我有3个标签。该动作条也有一个搜索查看，所以当进行检索，第三个选项卡切换出与搜索的结果。
我能够从搜索查看intput得到，但我无法转出的第三个标签时，我有一个搜索结果。我用这作为一个例子：
<一href=\"http://stackoverflow.com/questions/18120510/dynamically-changing-the-fragments-inside-a-fragment-tab-host\">Dynamically改变片段片段选项卡里面的主机？
我的问题是，当我尝试去的第三个标签的参考，我用getSupportFragmentManager（）。findFragmentByTag（）返回的片段总是空。
我的基本容器，有助于在标签交换多个片段：
公共类BaseContainerFragment扩展片段{ 公共无效replaceFragment（片段片段，布尔addToBackStack）{
FragmentTransaction交易= getChildFragmentManager（）调用BeginTransaction（）。
如果（addToBackStack）{
transaction.addToBackStack（NULL）;
}
transaction.replace（R.id.container_framelayout，片段）;
器transaction.commit（）;
getChildFragmentManager（）executePendingTransactions（）。
} 公共布尔popFragment（）{
//Log.e(\"test，流行音乐的片段：+ getChildFragmentManager（）getBackStackEntryCount（））;
布尔isPop = FALSE;
如果（getChildFragmentManager（）getBackStackEntryCount（）方式＆gt; 0）{
isPop = TRUE;
getChildFragmentManager（）popBackStack（）。
}
返回isPop;
}
}
扩展BaseContainerFragment的容器
公共类LibraryContainerFragment扩展BaseContainerFragment { 私人布尔mIsViewInited; @覆盖
公共查看onCreateView（LayoutInflater充气器，容器的ViewGroup，捆绑savedInstanceState）{
Log.e（测试，标签1 oncreateview）;
返回inflater.inflate（R.layout.container_fragment，NULL）;
} @覆盖
公共无效onActivityCreated（捆绑savedInstanceState）{
super.onActivityCreated（savedInstanceState）;
Log.e（测试，上的活动选项卡1容器创建）;
如果（！mIsViewInited）{
mIsViewInited = TRUE;
initView（）;
// setRetainInstance（真）;
}
} 私人无效initView（）{
Log.e（测试，标签1初始化视图）; replaceFragment（新LibraryFragment，FALSE）; }
}
用于转出片段（container_fragment.xml）的XML：
＆LT;？XML版本=1.0编码=UTF-8＆GT？;
＆LT;的FrameLayout的xmlns：机器人=http://schemas.android.com/apk/res/android
机器人：ID =@ + ID / container_framelayout
机器人：layout_width =match_parent
机器人：layout_height =match_parent＆GT;＆LT; /＆的FrameLayout GT;
我的主要活动：
公共类BookSetup扩展ActionBarActivity { //为了访问SlidingMenu库
私人SlidingMenu slidingMainMenu;
私人FragmentTabHost mTabHost;
私人SlidingMenu slidingContextMenuFavourites;
私人SlidingMenu slidingContextMenuMyPrayerBook;
私人SlidingMenu slidingContextMenuLibrary;
私人android.support.v4.app.FragmentManager fragmentManager; LibraryContainerFragment libraryContainerFragment;
@覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
//设置操作栏中可点击左上角的按钮
android.support.v7.app.ActionBar栏= getSupportActionBar（）; bar.setDisplayHomeAsUpEnabled（假）;
bar.setHomeButtonEnabled（真）;
bar.setIcon（R.drawable.main_menu）; //设置选项卡式浏览
bar.setDisplayShowTitleEnabled（假）;
//设置标签
fragmentManager = getSupportFragmentManager（）;
mTabHost =（FragmentTabHost）findViewById（android.R.id.tabhost）;
mTabHost.setup（这一点，fragmentManager，R.id.realtabcontent）; //添加标签
mTabHost.addTab（mTabHost.newTabSpec（最爱）。setIndicator（的getString（R.string.favourites））
FavouritesFragment.class，NULL）; mTabHost.addTab（mTabHost.newTabSpec（我的书）。setIndicator（的getString（R.string.my_book））
MyBookFragment.class，NULL）;
mTabHost.addTab（mTabHost.newTabSpec（库）。setIndicator（的getString（R.string.library））
LibraryContainerFragment.class，NULL）; mTabHost.setCurrentTab（2）;
// mTabHost。 //创建时，滑动动画活动启动
overridePendingTransition（R.anim.slide_in_from_right，R.anim.slide_out_to_left）;
} @覆盖
公共布尔onCreateOptionsMenu（菜单菜单）{ //充气菜单;如果是present这增加了项目操作栏。
。getMenuInflater（）膨胀（R.menu.main_menu_with_search_context_menu，菜单）;
SearchManager的SearchManager的=（SearchManager的）getSystemService（Context.SEARCH_SERVICE）;
//搜索查看搜索查看=（搜索查看）menu.findItem（R.id.action_search）.getActionView（）; 最终的菜单项searchMenuItem = menu.findItem（R.id.action_search）;
搜索查看=（android.support.v7.widget.SearchView）MenuItemCompat.getActionView（searchMenuItem）;
//搜索查看=（搜索查看）menu.findItem（R.id.action_search）.getActionView（）;
searchView.setSearchableInfo（SearchManager的
.getSearchableInfo（getComponentName（）））;
//searchView.requestFocus（）;
searchView.requestFocusFromTouch（）; //searchView.setIconifiedByDefault(true）;
//监听器操作栏中找到搜索输入，当放大镜
//点击
searchView.setOnQueryTextListener（新SearchView.OnQueryTextListener（）{ //当一个搜索字符串提交激活
@覆盖
公共布尔onQueryTextSubmit（查询字符串）{
// TODO：查询是从搜索视图中的文本，你点击搜索后， 如果（查询！= NULL）{
//如果找到结果，然后切换片段
如果（！sectionsFound.isEmpty（））{ //初始化搜索片段和发送数据的包吧
SearchLibraryResultFragment片段=新SearchLibraryResultFragment（）;
束束=新包（）;
bundle.putParcelableArrayList（价值观，
（ArrayList的＆LT ;?延伸Parcelable＆GT;）sectionsFound）;
bundle.putStringArrayList（名，sectionNames）;
fragment.setArguments（包）; mTabHost.setCurrentTab（2）;
libraryContainerFragment =（LibraryContainerFragment）fragmentManager.findFragmentByTag（库）;
（（BaseContainerFragment）libraryContainerFragment.getParentFragment（））.replaceFragment（片段，真实）;
返回true;
}
}）; }
}
这是始终处于BookSetup.java返回null行：
（（BaseContainerFragment）libraryContainerFragment.getParentFragment（））.replaceFragment（片段，真实）;
解决方案
正在使用 ChildFragmentManager 来取代你的片段吧？
这可能是你的问题，而不是
libraryContainerFragment =（LibraryContainerFragment）fragmentManager.findFragmentByTag（库）;
使用
libraryContainerFragment =（LibraryContainerFragment）getChildFragmentManager（）findFragmentByTag（库）。
I am working with the support library ActionBar because I'm using an older minimum SDK. In the activity, I am using FragmentTabHost because I have 3 tabs. The ActionBar also has a SearchView, so when a search is made, the 3rd tab is switched out with the results of the search.
I am able to get intput from the SearchView, but I am unable to switch out the 3rd tab when I have a search result. I am using this as an example: Dynamically changing the fragments inside a fragment tab host?
My problem is that when I try to get a reference to the 3rd tab, and I use getSupportFragmentManager().findFragmentByTag() , the fragment being returned is always null.
My base container that helps in swapping multiple fragments in a tab:
public class BaseContainerFragment extends Fragment{
public void replaceFragment(Fragment fragment, boolean addToBackStack) {
FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
if (addToBackStack) {
transaction.addToBackStack(null);
}
transaction.replace(R.id.container_framelayout, fragment);
transaction.commit();
getChildFragmentManager().executePendingTransactions();
}
public boolean popFragment() {
//Log.e("test", "pop fragment: " + getChildFragmentManager().getBackStackEntryCount());
boolean isPop = false;
if (getChildFragmentManager().getBackStackEntryCount() > 0) {
isPop = true;
getChildFragmentManager().popBackStack();
}
return isPop;
}
}
A container that extends BaseContainerFragment
public class LibraryContainerFragment extends BaseContainerFragment {
private boolean mIsViewInited;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Log.e("test", "tab 1 oncreateview");
return inflater.inflate(R.layout.container_fragment, null);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Log.e("test", "tab 1 container on activity created");
if (!mIsViewInited) {
mIsViewInited = true;
initView();
// setRetainInstance(true);
}
}
private void initView() {
Log.e("test", "tab 1 init view");
replaceFragment(new LibraryFragment, false);
}
}
The xml used to switch out fragments (container_fragment.xml):
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/container_framelayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>
My main activity:
public class BookSetup extends ActionBarActivity {
// For accessing SlidingMenu library
private SlidingMenu slidingMainMenu;
private FragmentTabHost mTabHost;
private SlidingMenu slidingContextMenuFavourites;
private SlidingMenu slidingContextMenuMyPrayerBook;
private SlidingMenu slidingContextMenuLibrary;
private android.support.v4.app.FragmentManager fragmentManager;
LibraryContainerFragment libraryContainerFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Settings for the clickable top-left button in the action bar
android.support.v7.app.ActionBar bar = getSupportActionBar();
bar.setDisplayHomeAsUpEnabled(false);
bar.setHomeButtonEnabled(true);
bar.setIcon(R.drawable.main_menu);
// Setting up tabbed navigation
bar.setDisplayShowTitleEnabled(false);
// Setting up tabs
fragmentManager = getSupportFragmentManager();
mTabHost = (FragmentTabHost)findViewById(android.R.id.tabhost);
mTabHost.setup(this, fragmentManager, R.id.realtabcontent);
// Add tabs
mTabHost.addTab(mTabHost.newTabSpec("Favourites").setIndicator(getString(R.string.favourites) ),
FavouritesFragment.class, null);
mTabHost.addTab(mTabHost.newTabSpec("My Book").setIndicator(getString(R.string.my_book) ),
MyBookFragment.class, null);
mTabHost.addTab(mTabHost.newTabSpec("Library").setIndicator(getString(R.string.library) ),
LibraryContainerFragment.class, null);
mTabHost.setCurrentTab(2);
//mTabHost.
// Creates a sliding animation when activity is started
overridePendingTransition(R.anim.slide_in_from_right, R.anim.slide_out_to_left);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main_menu_with_search_context_menu, menu);
SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
//SearchView searchView = (SearchView) menu.findItem(R.id.action_search).getActionView();
final MenuItem searchMenuItem = menu.findItem(R.id.action_search);
searchView = (android.support.v7.widget.SearchView) MenuItemCompat.getActionView(searchMenuItem);
//searchView = (SearchView)menu.findItem(R.id.action_search).getActionView();
searchView.setSearchableInfo(searchManager
.getSearchableInfo(getComponentName()));
//searchView.requestFocus();
searchView.requestFocusFromTouch();
//searchView.setIconifiedByDefault(true);
// Listener for the search input found in the action bar, when the magnifying glass is
// clicked
searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
// Activated when a search string is submitted
@Override
public boolean onQueryTextSubmit(String query) {
// TODO : query is the text from the search view after you clicked search
if(query != null){
// If results are found, then switch the fragments
if(!sectionsFound.isEmpty()){
// Initialize the search fragment and send bundles of data to it
SearchLibraryResultFragment fragment = new SearchLibraryResultFragment();
Bundle bundle = new Bundle();
bundle.putParcelableArrayList("values",
(ArrayList<? extends Parcelable>) sectionsFound);
bundle.putStringArrayList("names", sectionNames);
fragment.setArguments(bundle);
mTabHost.setCurrentTab(2);
libraryContainerFragment = (LibraryContainerFragment)fragmentManager.findFragmentByTag("Library");
((BaseContainerFragment) libraryContainerFragment.getParentFragment() ).replaceFragment(fragment,true );
return true;
}
});
}
}
This is the line that always returns null in BookSetup.java:
((BaseContainerFragment) libraryContainerFragment.getParentFragment() ).replaceFragment(fragment,true );
解决方案
You are using the ChildFragmentManager to replace your Fragments right?
That might be your problem, instead of
libraryContainerFragment = (LibraryContainerFragment)fragmentManager.findFragmentByTag("Library");
use
libraryContainerFragment = (LibraryContainerFragment) getChildFragmentManager().findFragmentByTag("Library");
这篇关于与getSupportFragmentManager时（findFragmentByTag（）的返回null）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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