Read and write data to Cloud Firestore in Android

Question

Hi I want to read and write data using Firebase Firestore.

1- I `added Firebase to my project (using this instruction)

2- I added Firestore to my project (using this instruction)

I can write and then read data, but the read and write operation are locally and my Firestore database not changing.

• I have added google-services.json to my app directory
• I declared internet and network-state permission in manifest
• My device is connected to internet
• My Firestore database is in test mode (allow read, write)

This is my build.gradle dependency:

implementation platform('com.google.firebase:firebase-bom:29.1.0')
implementation 'com.google.firebase:firebase-analytics'
implementation 'com.google.firebase:firebase-firestore'

This is my code to add data to Firestore database:

private void writeData()
{
    FirebaseFirestore db = FirebaseFirestore.getInstance();
    
    Map<String, Object> user = new HashMap<>();
    user.put("first", "Ada");
    user.put("last", "Lovelace");
    user.put("born", 1815);

    db.collection("purchased")
            .add(user)
            .addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                @Override
                public void onSuccess(DocumentReference documentReference) {
                    Toast.makeText(MainActivity.this,"done",Toast.LENGTH_SHORT).show();
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Toast.makeText(MainActivity.this,"failed",Toast.LENGTH_SHORT).show();
                }
            });
}

And this is my code to read data:

private void readData()
{
    FirebaseFirestore db = FirebaseFirestore.getInstance();
    db.collection("purchased")
            .get()
            .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                @Override
                public void onComplete(@NonNull Task<QuerySnapshot> task) {
                    if (task.isSuccessful()) {
                        for (QueryDocumentSnapshot document : task.getResult()) {
                            Toast.makeText(MainActivity.this,document.getId() + " => " + document.getData(),Toast.LENGTH_LONG).show();
                        }
                    } else {
                        Toast.makeText(MainActivity.this,"Error getting documents: "+ task.getException().getMessage().toString(),Toast.LENGTH_LONG).show();
                    }
                }
            });
}

While writing data, even callbacks are not calling (neither onSuccess nor onFailue) and no toast is displaying, but when I read data the toast display my data correctly, but everything is offline and no changes made to my Firestore database, what's the problem?