Android: How to get all child list from Firebase to arraylist

Question

This is my structure Firebase database. I need get all order details (orderdate, ordername etc) to arraylist. But I don't know how much orders (order1, order2...) will be.

database strukture

This is my model class:

public class OrderDetails {
String orderdate,ordername;

public OrderDetails() {
}

public OrderDetails(String orderdate, String ordername) {
    this.orderdate = orderdate;
    this.ordername = ordername;
}

public String getOrderdate() {
    return orderdate;
}

public void setOrderdate(String orderdate) {
    this.orderdate = orderdate;
}

public String getOrdername() {
    return ordername;
}

public void setOrdername(String ordername) {
    this.ordername = ordername;
} }

This is my code:

 ref = FirebaseDatabase.getInstance().getReference().child("Customers").child(cityID).child(customerID).child("orders");

List<OrderDetails> orderList = new ArrayList<>();

ref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

    for( DataSnapshot postSnapshot : dataSnapshot.getChildren()){
        OrderDetails details = postSnapshot.getValue(OrderDetails.class);
        orderList.add(details);
        toast.makeText(getContext(), orderList, Toast.LENGTH_SHORT).show();
    }
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {

} });

But this code not working. Need help please!

Why do you say it's not working? Do you have an error? How did you test it? — Alex Mamo, Feb 15 '19 at 15:07
I add toast toast.makeText(getContext(), orderList, Toast.LENGTH_SHORT).show(); and get next date: [com.example.janedtj.shopapk.models.OrderDetails@8a15b85, com.example.janedtj.shopapk.models.OrderDetails@474adda] — janedtj, Feb 15 '19 at 15:13
If you a re using `Toast.makeText(getContext(), details.getOrdername(), Toast.LENGTH_SHORT).show();`, does it toast the name of the order? — Alex Mamo, Feb 15 '19 at 15:24
When I want to get size of list listSize = orderList.size(); I get 0, but in toast I get name of order. Why list size is 0? — janedtj, Feb 15 '19 at 15:43

Alex Mamo · Accepted Answer · 2019-02-15T16:04:49.833

0

The problem in your code is that your are passing as the second argument in your makeText() method a List object instead of a String. The following message that you get:

[com.example.janedtj.shopapk.models.OrderDetails@8a15b85, com.example.janedtj.shopapk.models.OrderDetails@474adda]

Is in fact what toString() method returns. It represents the address of the List object from the memory. If you want to display for example, what your order name property holds, please change the following line of code:

Toast.makeText(getContext(), orderList, Toast.LENGTH_SHORT).show();

to

Toast.makeText(getContext(), details.getOrdername(), Toast.LENGTH_SHORT).show();

Please also note, if you want to get the size of the list, the following lines of code is required:

for( DataSnapshot postSnapshot : dataSnapshot.getChildren()){
    OrderDetails details = postSnapshot.getValue(OrderDetails.class);
    orderList.add(details);
}
Toast.makeText(getContext(), String.valueOf(orderList.size()), Toast.LENGTH_SHORT).show();

And should be placed outside the for loop as you can see.

edited Feb 15 '19 at 16:04

answered Feb 15 '19 at 15:43

Alex Mamo

130,605
17
163
193

Please see my updated answer. Does it work now? – Alex Mamo Feb 15 '19 at 16:05
Size is 0 again. – janedtj Feb 15 '19 at 16:11
Please add to your question the entire code that you are using for that. – Alex Mamo Feb 15 '19 at 16:12
It's working now. Thank you so much. But when I added this line Toast.makeText(getContext(), String.valueOf(orderList.size()), Toast.LENGTH_SHORT).show(); outside addValueEventListener, size was 0. Why? – janedtj Feb 15 '19 at 16:30
Because of [this](https://stackoverflow.com/questions/47847694/how-to-return-datasnapshot-value-as-a-result-of-a-method/47853774). You're welcome, cheers! – Alex Mamo Feb 15 '19 at 16:39
Thank you!! I use this method and it's work great but now I don't now how I can use this date outside readDate()? – janedtj Feb 15 '19 at 17:35
This question is not related with the initial one. In order to follow the rules of this comunity, please post another fresh question, so me and other Firebase developers can help you. – Alex Mamo Feb 15 '19 at 19:16
1

Ok, thank you! :) I created a new question. – janedtj Feb 15 '19 at 19:42
I'll take a look and if I'll know the answer, I'll write it to you. – Alex Mamo Feb 16 '19 at 16:37

Android: How to get all child list from Firebase to arraylist

1 Answers1