Message passing between Android fragment

1. Define an internal interface in fragment, in the fragment initialization method, convert the parent activity to this interface, assign the value to the member variable

 Public classDummyfragmentextendslistfragment {Someeventlistener listener;  Public InterfaceSomeeventlistener { Public voidOnsomeevent (intArg); } @Override Public voidOnattach (activity activity) {Super. Onattach (activity); Try{Listener=(Someeventlistener) activity; } Catch(classcastexception e) {Throw Newclasscastexception (activity.tostring ()+ "must implement Someeventlistener"); }    }    ...}

2. Parent activity must implement this interface

 Public Static class extends Activity     Implements Dummyfragment.someeventlistener {    ...          Public void onsomeevent (int  arg) {        //  parameters are passed in, And then call each fragment method here to pass the message     }}

3. In the corresponding event method of fragment, the calling interface notifies the parent activity

    @Override    publicvoidintlong  id) {        // Send the event to the host activity         listener.onsomeevent (position);    }

3. In the parent activity, after getting each fragment, call the corresponding fragment method in the interface method

 Public Static classMainactivityextendsActivityImplementsDummyfragment.someeventlistener {... Public voidOnsomeevent (intArg) {        //parameters are passed in, and then the various fragment methods are called here to pass the message.Articlefragment Articlefrag =(articlefragment) Getsupportfragmentmanager (). Findfragmentbyid (r.id.article_fragment); if(Articlefrag! =NULL) {Articlefrag.updatearticleview (position); } Else{articlefragment newfragment=Newarticlefragment (); Bundle args=NewBundle ();            Args.putint (Articlefragment.arg_position, POSITION);                    Newfragment.setarguments (args); Fragmenttransaction Transaction=Getsupportfragmentmanager (). BeginTransaction ();            Transaction.replace (R.id.fragment_container, newfragment); Transaction.addtobackstack (NULL);        Transaction.commit (); }    }}

In fact, the entire mechanism, is the activity in the creation of these fragment, as a member of the fragment variables, in the fragment when the change, can be notified by the agreed interface method, these agreed interface methods are defined by the fragment, Implemented by the activity.

Message passing between Android fragment