My app is a monthly basis app. like every 1st of the month my app should do the calculations and update the data in firebase.. as there is no function like that I'm using a button(reset) on which when clicked do the calculations and update in Firebase but I don't know how to update all date child in all nodes please help me.

Till now I have tried this.

datarefoutstd = database.getReference("outstdln");

datarefoutstd.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot snapshot) {
        for (DataSnapshot outsnapshot: snapshot.getChildren()) {
            outsnapshot.child("date").setValue(snapshot.getValue(Long.class) 1);

        }
    }

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

    }
});

CodePudding user response：

To increment by one the value of the date property within all nodes, please use the following lines of code:

DatabaseReference db = FirebaseDatabase.getInstance().getReference();
DatabaseReference outstdlnRef = db.child("outstdln");
outstdlnRef.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DataSnapshot> task) {
        if (task.isSuccessful()) {
            for (DataSnapshot ds : task.getResult().getChildren()) {
                ds.child("date").getRef().setValue(ServerValue.increment(1));
            }
        } else {
            Log.d("TAG", task.getException().getMessage()); //Never ignore potential errors!
        }
    }
});

This code will work only if you change the type of the date property from String to a number. It's really a bad practice to store numbers as strings. You should always store the data according to its correct data type.