Firebase 实时数据库 DataSnapshot only 读取子项中的最后一个值

Question

I'm calling addValueEventListener inside the button click, but this method only reads the last item in the node. I want to read all the child value in the node What went wrong here?

btnorder.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {

                    databaseReference.addValueEventListener(new ValueEventListener() {
                        @Override
                        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                            for(DataSnapshot dataSnapshot1:dataSnapshot.getChildren())
                            {
                                SelectedItems si=dataSnapshot1.getValue(SelectedItems.class);
                                si.getItemname();
                                Toast.makeText(MyBookedItems.this, ""+si.getItemname(), Toast.LENGTH_SHORT).show();
                            }
                        }

                        @Override
                        public void onCancelled(@NonNull DatabaseError databaseError) {

                        }
                    });

                }
        });

Answer 1

I think you can create an array list and put all snapshot data into it, and then you can find the last data of the list with the value you find by subtracting one from the length of the list. Sorry for my bad English :( I have tried to explain in the solution in the code below)

    ArrayList<SelectedItems> selectedItems = new ArrayList<SelectedItems>();
for(DataSnapshot dataSnapshot1:dataSnapshot.getChildren())
 {
     SelectedItems si=dataSnapshot1.getValue(SelectedItems.class);
     selectedItems.add(si);
   }
selectedItems.get(selectedItems.size());

Answer 2

它读取了所有值，但我将输出作为 Toast 消息，因此我只能看到最后一个值）