Android Save fragment Toggle State Instance Code _android

Objective

Frequent switching fragment can lead to frequent release and creation, and if fragment experience is very bad, share a method here.

Body

First, the application scene

1, do not use Viewpager

2, can not use replace to switch fragment, will cause fragment release (call Ondestroyview)

Second, realize

1, XML

<linearlayout xmlns:android= "http://schemas.android.com/apk/res/android" android:layout_width= "Match_parent" android:layout_height= "match_parent" android:orientation= "vertical" > <framelayout android:id= "@+id/" Container "android:layout_width=" match_parent "android:layout_height=" 0dip "android:layout_weight=" 1.0 "> </F ramelayout> <radiogroup android:id= "@+id/main_radio" android:layout_width= "Fill_parent" Android:layout_heigh t= "Wrap_content" android:layout_gravity= "bottom" android:gravity= "bottom" android:layout_marginbottom= " -6DP" Andro
   id:orientation= "Horizontal" > <radiobutton android:id= "@+id/radio_button0" style= "@style/main_tab_bottom" android:drawabletop= "@drawable/bottom_1"/> <radiobutton android:id= "@+id/radio_button1" style= "@style/ma
   In_tab_bottom "android:drawabletop=" @drawable/bottom_2 "/> <radiobutton android:id=" @+id/radio_button2 " style= "@style/main_tab_bottom" Android:drawabletop= "@drawable/bottom_3"/> <radiobutton android:id= "@+id/radio_button3" style= "@style/main_tab_bot Tom "android:drawabletop=" @drawable/bottom_4 "/> <radiobutton android:id=" @+id/radio_button4 "style=" @st Yle/main_tab_bottom "android:drawabletop=" @drawable/bottom_5 "/> </RadioGroup> </LinearLayout>

Code Description:

Very common bottom put 5 radiobutton, click to switch to different fragment.

2. Activity

Set Setoncheckedchangelistener event for RadioButton, other code:

 public void OnCheckedChanged (Compoundbutton buttonview, Boolean ischecked) {
  if (ischecked) {
   Fragment Fragment = (Fragment) mfragmentpageradapter.instantiateitem (Mcontainer, Buttonview.getid ());
   Mfragmentpageradapter.setprimaryitem (Mcontainer, 0, fragment);
   Mfragmentpageradapter.finishupdate (Mcontainer);
  }

 Private Fragmentpageradapter Mfragmentpageradapter = new Fragmentpageradapter (Getsupportfragmentmanager ()) {

  @ Override public
  Fragment getitem (int position) {
   switch (position) {case
   R.id.radio_button1:
    return new Fragment1 ();
   Case R.id.radio_button2: Return
    new Fragment2 ();
   Case R.ID.RADIO_BUTTON3: Return
    new Fragment3 ();
   Case R.ID.RADIO_BUTTON4: Return
    new Fragment4 ();
   Case R.ID.RADIO_BUTTON0:
   default: Return
    new Fragment0 ();
   }

  @Override public
  int GetCount () {return
   5;
  }
 };

Code Description:

Instantiateitem find fragment from Fragmentmanager, can't find GetItem new one, Setprimaryitem set hide and display, finally Finishupdate commit TRANSACTION, Mcontainer is the framelayout in XML.

Three, Fragmentpageradapter core code

 @Override public Object Instantiateitem (viewgroup container, int position) {if (mcurtransaction = null) {MCURTR
  Ansaction = Mfragmentmanager.begintransaction ();

  Final Long itemId = Getitemid (position);
  Do we already have this fragment?
  String name = Makefragmentname (Container.getid (), itemId);
  Fragment Fragment = Mfragmentmanager.findfragmentbytag (name);
   if (fragment!= null) {if (DEBUG) log.v (TAG, "Attaching Item #" + ItemId + ": f=" + fragment);
  Mcurtransaction.attach (fragment);
   else {fragment = GetItem (position);
   if (DEBUG) log.v (TAG, "adding Item #" + ItemId + ": f=" + fragment);
  Mcurtransaction.add (Container.getid (), Fragment, Makefragmentname (Container.getid (), itemId));
   } if (fragment!= Mcurrentprimaryitem) {fragment.setmenuvisibility (false);
  Fragment.setuservisiblehint (FALSE);
 return fragment; @Override public void Destroyitem (ViewGroup container, int position, object) {if (mcurtransaction = = null) {mcurtransaction = Mfragmentmanager.begintransaction (); } if (DEBUG) log.v (TAG, "Detaching Item #" + getitemid (position) + ": f=" + object + "v=" + ((Fragment) object). Getv
  Iew ());
 Mcurtransaction.detach ((Fragment) object); @Override public void Setprimaryitem (ViewGroup container, int position, object object) {Fragment Fragment = (fragm
  ENT) object; if (fragment!= Mcurrentprimaryitem) {if (Mcurrentprimaryitem!= null) {mcurrentprimaryitem.setmenuvisibility (FAL
    SE);
   Mcurrentprimaryitem.setuservisiblehint (FALSE);
    } if (fragment!= null) {fragment.setmenuvisibility (true);
   Fragment.setuservisiblehint (TRUE);
  } Mcurrentprimaryitem = fragment; @Override public void Finishupdate (ViewGroup container) {if (mcurtransaction!= null) {Mcurtransaction.comm
   Itallowingstateloss ();
   Mcurtransaction = null;
  
Mfragmentmanager.executependingtransactions (); } public void Setmenuvisibility (Boolean menuvisible) {
Super.setmenuvisibility (menuvisible);
if (This.getview ()!= null)
This.getview (). setvisibility (menuvisible? View.VISIBLE:View.GONE);
}
 }

The Fragmentpageradapter is a support package with its own class.

Iv. attention

Before the simulation of their own viewpager with attach, setmenuvisibility, setuservisiblehint to control the display of fragment hidden, often appear fragment overlapping phenomenon, very headache, After this change, no overlap has been found at this time.

End: The above is an example of Android Fragment, hoping to help students in need.