Question

下午好。每当我显示firebase的数据时，我都会遇到问题。它显示在recyclerview中，但recyclerview中的排列必须是最新日期。

日期2/1/2018必须是列表中的第一个。以下是我如何选择数据的代码。

myRef = FirebaseDatabase.getInstance().getReference("complaints");


        myRef.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                try{


                    list = new ArrayList<Blog>();
                    for(DataSnapshot dataSnapshot1 :dataSnapshot.getChildren()){

                        Blog value = dataSnapshot1.getValue(Blog.class);
                        Boolean Posted = value.getPosted();
                        String complaint_type = value.getComplaintType();

                        if (Posted== true && complaint_type.equals("Civic Complaint")) {
                            int ComplaintNo = value.getComplaintNo();
                            String Description = value.getDescription();
                            String Date = value.getDate();
                            String MediaURL = value.getMediaURL();
                            String Time = value.getTime();
                            String Address = value.getAddress();
                            int count_satisfiedd = value.getCount_Satisfied();
                            int count_dissatisfied = value.getCount_Dissatisfied();
                            boolean posted = value.getPosted();


                            Blog fire = new Blog();
                            fire.setComplaintNo(ComplaintNo);
                            fire.setDescription(Description);
                            fire.setDate(Date);
                            fire.setMediaURL(MediaURL);
                            fire.setTime(Time);
                            fire.setAddress(Address);
                            fire.setPosted(posted);
                            fire.setCount_Satisfied(count_satisfiedd);
                            fire.setCount_Dissatisfied(count_dissatisfied);
                            list.add(fire);
                        }

                    }

                    RecyclerAdapter recyclerAdapter = new RecyclerAdapter(list,getActivity());
                    RecyclerView.LayoutManager recyce = new GridLayoutManager(getActivity(),1);
                    recyclerView.setLayoutManager(recyce);
                    recyclerView.setItemAnimator( new DefaultItemAnimator());
                    recyclerView.setAdapter(recyclerAdapter);


                }catch (Exception e){


                }

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

这是数据库：

"complaints" : [ null, {
    "Address" : "Earth Street ",
    "CivicCategory" : "",",
    "ComplaintNo" : 1,
    "ComplaintType" : "",
    "Date" : "02 / 01 /2018",
    "Description" : ".",
    "MediaType" : "Image",
    "NearIn" : "Palengke ",
    "Posted" : true,
    "Time" : "11:42 AM"
  }, {
    "Address" : "Mars Street ",
    "CivicCategory" : " ",
    "ComplainantID" : "voter1",
    "ComplaintNo" : 2,
    "ComplaintType" : "",
    "Count_Resolved" : 0,
    "Count_Solved" : 0,
    "Date" : "01 / 03 /2018",
    "Description" : "
    "Posted" : true,
    "Time" : "11:43 AM"
  } ],

我怎样才能得到预期的结果？

感谢您的帮助

Answer 1

您可以在将列表传递给适配器之前将其反转

Collections.reverse(yourList);  //   <---- reverse the list

RecyclerAdapter recyclerAdapter = new RecyclerAdapter(list,getActivity());
RecyclerView.LayoutManager recyce = new GridLayoutManager(getActivity(),1);
recyclerView.setLayoutManager(recyce);
recyclerView.setItemAnimator( new DefaultItemAnimator());
recyclerView.setAdapter(recyclerAdapter);

Answer 2

我想，您可以采用以下两种方式之一，

单向 -

在arraylist中插入值后，按“date”键对其进行排序

Collections.sort(arrayList, new Comparator<ClassObject>() {
@Override
    public int compare(ClassObject o1, ClassObject o2) {
        // here you need to convert string to date format
        return o1.getDate().compareTo(o2.getDate());
    }
});

另一种方式 -

在firebase数据库中插入数据时，使用timestamp格式或按字典顺序排序的字符串，因为firebase数据库按字典顺序排序。（当前“日期”值格式不是按字典顺序排序的。

然后你的查询就像，

ref.orderByChild("Date")

我附上了一张用“timestamp”键的图片。我正在使用这个获得排序结果。

根据您的结构，您可能需要做一些合乎逻辑的事情。

通过降序日期键获取firebase数据顺序

2 个答案: