Android Studio Value Increment In Firebase

Can anyone teach me how to update my Firebase value when I click on my Android Studio App? There is no need to retrieve and display the data. Just an incremental of value in my Fir

Solution 1:

In order to increment a value in a Firebase database, first of all, you need to retrieve that value. There is no way to increment a value without knowing it. To achieve this, I definitely recommend you to use Firebase Transaction.

Let's take an example. Let's assume we want to increment a counter. In order to achieve this, please use the following code to set the default value of the counter.

DatabaseReferencerootRef= FirebaseDatabase.getInstance().getReference();
rootRef.child("score").setValue(1);

Assuming that the score field is of type Integer, to use transactions, please use the following method:

publicstaticvoidsetScore(String operation) {
    DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
    DatabaseReference scoreRef = rootRef.child("score");
    scoreRef.runTransaction(newTransaction.Handler() {
        @OverridepublicTransaction.ResultdoTransaction(MutableData mutableData) {
            Integer score = mutableData.getValue(Integer.class);
            if (score == null) {
                returnTransaction.success(mutableData);
            }

            if (operation.equals("increaseScore")) {
                mutableData.setValue(score + 1);
            } elseif (operation.equals("decreaseScore")){
                mutableData.setValue(score - 1);
            }

            returnTransaction.success(mutableData);
        }

        @OverridepublicvoidonComplete(DatabaseError databaseError, boolean b, DataSnapshot dataSnapshot) {}
    });
}

Using transactions, you will avoid inconsistent results if users are trying to increase/decrease the score at the same time. So as a conclusion, call this method accordingly to your increase/decrease operation.

If you want to read the score, please use the following code:

DatabaseReferencerootRef= FirebaseDatabase.getInstance().getReference();
DatabaseReferencescoreRef= rootRef.child("score");
ValueEventListenereventListener=newValueEventListener() {
    @OverridepublicvoidonDataChange(DataSnapshot dataSnapshot) {
        Integerscore= dataSnapshot.getValue(Integer.class);
        Log.d("TAG", "score: " + score);
    }

    @OverridepublicvoidonCancelled(DatabaseError databaseError) {}
};
scoreRef.addListenerForSingleValueEvent(eventListener);

Solution 2:

1. Get the value from the database.
2. Make a simple while loop, with the number of increments you need. Declare the variable globally, not within the onCreate methods.
3. Set them back to the Database.

Solution 3:

You don't need to retrieve the value if you use ServerValue.increment(). Recently, It landed on Flutter in version firebase_database 4.1.

The way you can use is:

mRefChild.set(ServerValue.increment(1));