CODEWITHSUNDEEP
javaandroidfirebasefirebase-realtime-database
Anjesh Shrestha
Anjesh Shrestha

Reputation: 25

Java/Android - Error loading ArrayList as Object from Firebase

Been trying to solve this Firebase loading arraylist problem for a while now but no idea how to get it solved.

Object Class

public class Book {
    private String title;
    private String author;
    private String ISBN;
    private String photo;
    private String ownerEmail;
    private String ownerID;
    private String BookID;
    private Date returnDate;
    private Status status;
    private String borrowerID;

    public Book(){}
    public Book(String title, String author, String ISBN, String photo, String ownerEmail, String ownerID) {
        this.title = title;
        this.author = author;
        this.ISBN = ISBN;
        this.photo = photo;
        this.ownerEmail = ownerEmail;
        this.ownerID = ownerID;
        this.status = Status.Available;
        if(this.BookID == null || this.BookID.isEmpty())
            this.BookID = UUID.randomUUID().toString();
    }
    public enum Status{
        Available,
        Requested,
        Accepted,
        Borrowed
    }

I have getter and setter for all the variables, and what I'm doing is load this information from firebase using the code:

 public void loadMyBookFromFirebase(){
        final ArrayList<Book> bookList = new ArrayList<>();

        DatabaseReference userReference = FirebaseDatabase.getInstance().getReference().child("users").child(this.userID).child("myBooks");
        userReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                Log.d("testing","books" + dataSnapshot.toString());
                if(dataSnapshot.exists()) {
                    try {
                        for (DataSnapshot books : dataSnapshot.getChildren()) {
                            Book book = dataSnapshot.getValue(Book.class);
                            Log.d("testing","books" + book.getAuthor());
                            //load book into ListView
                        }
                    } catch (Exception e){
                        e.printStackTrace();
                    }
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Log.w("testing","Error: ", databaseError.toException());
            }
        });
    }

this is my firebase database firebase database i keep getting a Can't convert object of type java.util.ArrayList to type com.example.cmput301w19t15.Book

error on the line Book book = dataSnapshot.getValue(Book.class); im not sure why i am getting the convert object error, i do not want to search for individual variables and set them, which defeat the purpose of the object class

I would really like some insight on this

Upvotes: 1

Views: 65

Answers (1)

Alex Mamo
Alex Mamo

Reputation: 138824

To solve this, please change the following line of code:

Book book = dataSnapshot.getValue(Book.class);

to

Book book = books.getValue(Book.class);

You need to get the data from the books object and not from the dataSnapshot object.

Upvotes: 1

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