Firebase儿童活动listerner

Question

我正在尝试使用firebase使用子事件listerner但是它在activty上运行已经开始并将数据添加到我的领域

是否有任何方法只有在数据更改时才能运行？

我在其中运行oncreate

chatchildevntlistener = chatlistreference.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                Constant.l("Add Changed Listerner Running");
                Conversion_List chatconbersionlist = dataSnapshot.getValue(Conversion_List.class);
                if (chatconbersionlist.getReceiverid().equals(Session.getUserID(getApplicationContext())) && chatconbersionlist.getSenderid().equals(getIntent().getStringExtra("rid"))) {
                    chatrealm = Realm.getDefaultInstance();
                    chatrealm.beginTransaction();
                    final Chat_history_pojo chatupdatepojo = chatrealm.createObject(Chat_history_pojo.class);
                    int nextID = chatrealm.where(Chat_history_pojo.class).max("chatnumber").intValue() + 1;
                    chatupdatepojo.setChatnumber(nextID);
                    chatupdatepojo.setSenderid(chatconbersionlist.getSenderid());
                    chatupdatepojo.setReceiverid(chatconbersionlist.getReceiverid());
                    chatupdatepojo.setTimeofthemessage(chatconbersionlist.getTimeofthemessage());
                    chatupdatepojo.setType(chatconbersionlist.getType());
                    chatupdatepojo.setMessage(chatconbersionlist.getMessage().replace("$", " "));
                    chatupdatepojo.setSender_profile(chatconbersionlist.getSender_profile());
                    chatupdatepojo.setReciever_profile(chatconbersionlist.getReciever_profile());
                    chatupdatepojo.setImageprice("0");
                    chatupdatepojo.setReadstatus(0);
                    if (!chatconbersionlist.getPoofingtext().equals("0")) {
                        chatupdatepojo.setPoofingtext(Integer.parseInt(chatconbersionlist.getPoofingtext()));
                        Intent poofingintent = new Intent(getApplicationContext(), Poofing_Receiver.class);
                        poofingintent.putExtra("rid", chatconbersionlist.getReceiverid());
                        poofingintent.putExtra("chatnumberposition", nextID);
                        PendingIntent poofingpendingintent = PendingIntent.getBroadcast(getApplicationContext(), nextID, poofingintent, 0);
                        AlarmManager poofingalaramanager = (AlarmManager) getSystemService(ALARM_SERVICE);
                        poofingalaramanager.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + Integer.parseInt(chatconbersionlist.getPoofingtext()) * 1000, poofingpendingintent);
                    }
                    chatrealm.commitTransaction();
                    chatrealm.close();
                }
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {
//                Constant.l(dataSnapshot.toString());
            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {
            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Constant.l(databaseError.toString());
            }
        });
        chatlistreference.addChildEventListener(chatchildevntlistener);