Android - Return boolean value relative Firebase

Question

public boolean checkGold(final int gold){
    mRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String value = dataSnapshot.getValue(String.class);
            goldparse = Integer.parseInt(value);
            if (gold > goldparse){
                /*Return*/
            }
        }
        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    });
    return false;
}

I have method to check gold in outside but how to return false in method onDataChange. Thanks.

Unfortunately, you cannot do that. Another way is to create custom function and call it from inside `onDataChange()` — koceeng, Mar 09 '17 at 09:08
By the way, the code sample you provide will always return false, isn't it? — koceeng, Mar 09 '17 at 09:10
Yeah, I want to compare input value(gold) with gold from database in firebase to minus gold if input value less. => return true. And vice versa is return false — Chung Phùng Văn, Mar 09 '17 at 09:15

score 1 · Answer 1 · edited May 23 '17 at 12:32

Firebase Database is asyncronous, and its flow is outside the regular flow that we usually do. In this post, I tried to explain that (just for information)

And in this case, you do something like this, right?

boolean iWantValue = checkGold(10);
if (iWantValue) {
    // do someting
} else {
    // do something else
}
...
public boolean checkGold(final int gold) {
    ... // content here are still the same as mentioned in question
}

But if we know it is asyncronous, it should be like this:

int currentGold = 0; // place gold here so it can be accessed anywhere
...
// wherever you want to check gold, type this
currentGold = 10; // update this value first, right?
checkGold();
...
public void checkGold() {
    mRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String value = dataSnapshot.getValue(String.class);
            goldparse = Integer.parseInt(value);
            if (currentGold > goldparse){
                // do something
            } else {
                // do something here
            }
        }
        ...
    });
}

Or if you are like me who want something tidy:

public void checkGold() {
    mRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            doSomethingOrNot(Integer.parseInt(dataSnapshot.getValue(String.class)));
        }
        ...
    });
}

private void doSomethingOrNot(int goldparse) {
    if (currentGold > goldparse){
        // do something
    } else {
        // do something here
    }
}

It needs time to be familiar with this, but it's worth it. Hope this helps

Android - Return boolean value relative Firebase

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