导致 activity 召回 Firebase Android 的交易

Question

当我单击 rate_btn 以启动此 t运行saction 功能时。

它工作正常但在这个过程中它重新运行我的classactivity一次（我的classactivity重新运行s 每次使用 t运行saction）因此像我的 msg_ID 一样重置一切。

例如，我的 msg_ID 更改（由于使用运行dom）每次 class activity 是调用，所以当我运行 t运行saction 它工作但在 return 它运行 class activity 也因此改变我的 msg_ID还有

这是一个场景：

so when click this "rate" button it does the rating on the current msg_ID but when I click on it again, it rates a different msg_ID because of my get random msg_ID. I think this is caused when I call the onComplete method.

当我点击rate_btn

现在 class 重新运行我再次点击 rate_btn

它投了第一个 msg_id 然后当我再次点击 rate_btn 它投了第一个第二个键（因为它重新调用了 class activity 和 msg_id 改变了）

这是 t运行saction 的代码：

rate_btn.setOnClickListener(new OnClickListener(){
public void onClick(View v){
        Firebase upvoteref = new Firebase("https://myapp.firebaseio.com/"+msgID+"/upvotes"); 

        upvoteref.runTransaction(new Transaction.Handler() {
            @Override
            public Transaction.Result doTransaction(final MutableData currentData) {
                if (currentData.getValue() == null) {
                    currentData.setValue(1);
                } else {
                    currentData.setValue((Long) currentData.getValue() + 1);
                }

                return Transaction.success(currentData);
            }

            public void onComplete(FirebaseError firebaseError, boolean committed, DataSnapshot currentData) {
                if (firebaseError != null) {
                    System.out.println("Firebase counter increment failed.");
                } else {
                    System.out.println("Firebase counter increment succeeded.");
                }
            }
        });
    }

这是检索运行dom id 的代码：

    String msgID; //this variable is declare at the start of the class as a global variable.

    Firebase ref = new Firebase("https://myapp.firebaseio.com/"+msgID); 

    ref.addValueEventListener(new ValueEventListener() {

        public void onDataChange(DataSnapshot snapshot) {
            Iterable<DataSnapshot> ds = snapshot.getChildren();

            //getting maximum number of children
            long allNum = snapshot.getChildrenCount();
            int maxNum = (int)allNum;

            //getting the random integer from number of children
            int randomNum = new Random().nextInt(maxNum);

            Iterator<DataSnapshot> ids = ds.iterator();

            int count = 0;

            //has next will check if there are values in the next iteration , while count is used as a position substitute.
            while(ids.hasNext() && count < randomNum) {
                ids.next();
                count ++; // used as positioning.
            }           

            Map<String, Object> newPost = (Map<String, Object>) ids.next().getValue(); // ids will take the value in the iterator (iterate at key) 
            //getting the message from the key
            msgID = newPost.get("id").toString();
        }

有什么想法吗？

Answer 1

由于每次调用事务时消息 ID 都会更改，这是因为 addValueEventListener（它在调用事务时接受更改）。因此，为了解决这个问题，我添加了 addListenerForSingleValueEvent 而不是 addValueEventListener 并且它起作用了。

例如：

 ref.addListenerForSingleValueEvent(new ValueEventListener() {

    public void onDataChange(DataSnapshot snapshot) {
        Iterable<DataSnapshot> ds = snapshot.getChildren();

        //getting maximum number of children
        long allNum = snapshot.getChildrenCount();
        int maxNum = (int)allNum;

        //getting the random integer from number of children
        int randomNum = new Random().nextInt(maxNum);

        Iterator<DataSnapshot> ids = ds.iterator();

        int count = 0;

        //has next will check if there are values in the next iteration , while count is used as a position substitute.
        while(ids.hasNext() && count < randomNum) {
            ids.next();
            count ++; // used as positioning.
        }           

        Map<String, Object> newPost = (Map<String, Object>) ids.next().getValue(); // ids will take the value in the iterator (iterate at key) 
        //getting the message from the key
        msgID = newPost.get("id").toString();
    }`

导致 activity 召回 Firebase Android 的交易

Transaction causing activity to recall Firebase Android

java

android

transactions

firebase