如何获得内容片段在onTabChanged(字符串tabTag) [英] how to get the content fragment at onTabChanged(String tabTag)
问题描述
搜索,看到了类似的问题,几个帖子,但没有有效的解决方案。
张贴在这里,看看是否有人已经解决了。
有FragmentTabHost的片段,并试图获取当前选项卡的内容片段。
在mTabHost.setOnTabChangedListener的onTabChanged(字符串tabTag)
在frgmt = getChildFragmentManager()findFragmentByTag(tabTag)。返回null。
mTabHost.setOnTabChangedListener(新TabHost.OnTabChangeListener(){
@覆盖
公共无效onTabChanged(字符串tabTag){ 片段frgmt = getChildFragmentManager()findFragmentByTag(tabTag)。 }
});
在FragmentTabHost,其onTabChanged()调用doTabChanged(),其实例化内容片段,并添加与FragmentTransaction,或者如果该片段存在附加到它。
我想,当FragmentTabHost :: onTabChanged()调用到听者的onTabChanged(),该片段是仍然getChildFragmentManager()在FragmentManager没有准备好。
有没有办法从FragmentTabHost的获得mLastTab?它应该有目前的内容片段。
感谢您的帮助!
@覆盖
公共无效onTabChanged(字符串tabId){
如果(mAttached){
FragmentTransaction英尺= doTabChanged(tabId,NULL);
如果(英尺!= NULL){
ft.commit();
}
}
如果(mOnTabChangeListener!= NULL){
mOnTabChangeListener.onTabChanged(tabId);
}
}私人FragmentTransaction doTabChanged(字符串tabId,FragmentTransaction英尺){
TabInfo newTab = NULL;
的for(int i = 0; I< mTabs.size();我++){
TabInfo标签= mTabs.get(I)
如果(tab.tag.equals(tabId)){
newTab =标签;
}
}
如果(newTab == NULL){
抛出新IllegalStateException异常(无标签闻名标签+ tabId);
}
如果(mLastTab!= newTab){
如果(英尺== NULL){
英尺= mFragmentManager.beginTransaction();
}
如果(mLastTab!= NULL){
如果(mLastTab.fragment!= NULL){
ft.detach(mLastTab.fragment);
}
}
如果(newTab!= NULL){
如果(newTab.fragment == NULL){
newTab.fragment = Fragment.instantiate(mContext,
newTab.clss.getName(),newTab.args);
ft.add(mContainerId,newTab.fragment,newTab.tag);
}其他{
ft.attach(newTab.fragment);
}
} mLastTab = newTab;
}
返回英尺;
}
你可以在OntabChanged(看到的是ft.commit问题),然后我们称之为
如果(mOnTabChangeListener!= NULL){
mOnTabChangeListener.onTabChanged(tabId);
}
仍然没有因此创建标签片段,当我们试图让OnTabChnaged回调里面Tabfragement实例抛出空指针异常。
我的解决方案:
我们应该用这样两个片段之间通过活动交流。
下面是活动
公共类MainActivity扩展ActionBarActivity实现OnHeadlineSelectedListener {@覆盖
保护无效的onCreate(捆绑savedInstanceState){
super.onCreate(savedInstanceState);
的setContentView(R.layout.activity_main);
}
@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.menu_main,菜单);
返回true;
}@覆盖
公共布尔onOptionsItemSelected(菜单项项){
//处理动作栏项目点击这里。操作栏会
//自动处理上点击主页/向上按钮,只要
//你在AndroidManifest.xml中指定一个父活动。
INT ID = item.getItemId(); // noinspection SimplifiableIfStatement
如果(ID == R.id.action_settings){
返回true;
} 返回super.onOptionsItemSelected(项目);
}@覆盖
公共无效OnTabCompletelyChanged(字符串标签){
((MainActivityFragment)getSupportFragmentManager().findFragmentById(R.id.fragment)).OnTabChanged(tag);}
}
MainFragment抓住引片
公共类MainActivityFragment扩展片段{
私人FragmentTabHost mTabHost;
私人FragmentTab标签;
公共MainActivityFragment(){
}@覆盖
公共查看onCreateView(LayoutInflater充气器,容器的ViewGroup,
捆绑savedInstanceState){
视图V = inflater.inflate(R.layout.fragment_main,集装箱,FALSE); mTabHost =(FragmentTabHost)v.findViewById(android.R.id.tabhost);
mTabHost.setup(getActivity(),getChildFragmentManager(),android.R.id.tabcontent); mTabHost.addTab(
mTabHost.newTabSpec(TAB1)。setIndicator(标签1,NULL)
FragmentTab.class,NULL);
mTabHost.addTab(
mTabHost.newTabSpec(TAB2)。setIndicator(表2,NULL)
FragmentTab.class,NULL);
mTabHost.addTab(
mTabHost.newTabSpec(TAB3)。setIndicator(标签3,NULL)
FragmentTab.class,NULL); 返回伏;
}
公共无效OnTabChanged(字符串标签){
标签=(FragmentTab)getChildFragmentManager()findFragmentByTag(标签)。 //非空
}
}
FragmentTab:
公共类FragmentTab扩展片段{私人OnHeadlineSelectedListener mCallback;@覆盖
公共无效的onCreate(捆绑savedInstanceState){
super.onCreate(savedInstanceState);
}@覆盖
公共无效onAttach(活动活动){
super.onAttach(活动); //这将确保集装箱活动实施
//回调接口。如果不是,它抛出一个异常
尝试{
mCallback =(OnHeadlineSelectedListener)活性;
}赶上(抛出ClassCastException E){
抛出新ClassCastException异常(activity.toString()
+必须实现OnHeadlineSelectedListener);
}
}@覆盖
公共无效调用onStart(){
super.onStart();
mCallback.OnTabCompletelyChanged(this.getTag());
}公共字符串的getString(){
返回你好;
}
@覆盖
公共查看onCreateView(LayoutInflater充气器,容器的ViewGroup,
捆绑savedInstanceState){
视图V = inflater.inflate(R.layout.fragment_layout,集装箱,FALSE);
TextView的电视=(TextView中)v.findViewById(R.id.text);
tv.setText(this.getTag()+内容);
返回伏;
}}
Searched and saw a few posts for the similar question, but no working solution. Post here to see if someone have solved it.
Having FragmentTabHost in a fragment, and trying to get current tab's content fragment.
in mTabHost.setOnTabChangedListener's onTabChanged(String tabTag) the frgmt = getChildFragmentManager().findFragmentByTag(tabTag); returns null.
mTabHost.setOnTabChangedListener(new TabHost.OnTabChangeListener() {
@Override
public void onTabChanged(String tabTag) {
Fragment frgmt = getChildFragmentManager().findFragmentByTag(tabTag);
}
});
In FragmentTabHost, its onTabChanged() calls doTabChanged() which instantiates the content fragment and add with FragmentTransaction, or attach to it if the fragment exist.
I guess when FragmentTabHost::onTabChanged() calls into the listener's onTabChanged(), the fragment is still not ready in the FragmentManager by getChildFragmentManager().
Is there a way the get the mLastTab from the FragmentTabHost? It should have the current content fragment.
Thanks for the help!
@Override
public void onTabChanged(String tabId) {
if (mAttached) {
FragmentTransaction ft = doTabChanged(tabId, null);
if (ft != null) {
ft.commit();
}
}
if (mOnTabChangeListener != null) {
mOnTabChangeListener.onTabChanged(tabId);
}
}
private FragmentTransaction doTabChanged(String tabId, FragmentTransaction ft) {
TabInfo newTab = null;
for (int i=0; i<mTabs.size(); i++) {
TabInfo tab = mTabs.get(i);
if (tab.tag.equals(tabId)) {
newTab = tab;
}
}
if (newTab == null) {
throw new IllegalStateException("No tab known for tag " + tabId);
}
if (mLastTab != newTab) {
if (ft == null) {
ft = mFragmentManager.beginTransaction();
}
if (mLastTab != null) {
if (mLastTab.fragment != null) {
ft.detach(mLastTab.fragment);
}
}
if (newTab != null) {
if (newTab.fragment == null) {
newTab.fragment = Fragment.instantiate(mContext,
newTab.clss.getName(), newTab.args);
ft.add(mContainerId, newTab.fragment, newTab.tag);
} else {
ft.attach(newTab.fragment);
}
}
mLastTab = newTab;
}
return ft;
}
The problem as you can see is ft.commit in OntabChanged() and then we call
if (mOnTabChangeListener != null) {
mOnTabChangeListener.onTabChanged(tabId);
}
the tab fragment still not created hence throws null pointer exception when we try to get the instance of Tabfragement inside OnTabChnaged callback.
My Solution : we should use the way two fragments communicate with each other using activity.
Here is the activity
public class MainActivity extends ActionBarActivity implements OnHeadlineSelectedListener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void OnTabCompletelyChanged(String tag) {
((MainActivityFragment)getSupportFragmentManager().findFragmentById(R.id.fragment)).OnTabChanged(tag);
}
}
MainFragment Holding the Tabs
public class MainActivityFragment extends Fragment {
private FragmentTabHost mTabHost;
private FragmentTab tab;
public MainActivityFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_main, container, false);
mTabHost = (FragmentTabHost) v.findViewById(android.R.id.tabhost);
mTabHost.setup(getActivity(), getChildFragmentManager(), android.R.id.tabcontent);
mTabHost.addTab(
mTabHost.newTabSpec("tab1").setIndicator("Tab 1", null),
FragmentTab.class, null);
mTabHost.addTab(
mTabHost.newTabSpec("tab2").setIndicator("Tab 2", null),
FragmentTab.class, null);
mTabHost.addTab(
mTabHost.newTabSpec("tab3").setIndicator("Tab 3", null),
FragmentTab.class, null);
return v;
}
public void OnTabChanged(String tag) {
tab = (FragmentTab)getChildFragmentManager().findFragmentByTag(tag); // Not null
}
}
FragmentTab:
public class FragmentTab extends Fragment {
private OnHeadlineSelectedListener mCallback;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// This makes sure that the container activity has implemented
// the callback interface. If not, it throws an exception
try {
mCallback = (OnHeadlineSelectedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnHeadlineSelectedListener");
}
}
@Override
public void onStart() {
super.onStart();
mCallback.OnTabCompletelyChanged(this.getTag());
}
public String getString(){
return "hello";
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_layout, container, false);
TextView tv = (TextView) v.findViewById(R.id.text);
tv.setText(this.getTag() + " Content");
return v;
}}
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