吐司一直循环答案

【问题标题】：Toast keeps on loop吐司一直循环
【发布时间】：2021-01-29 02:57:51
【问题描述】：

我的 Toast 一直在运行或循环，我不明白为什么。

 private void fetchTheData() {
    //fetch subjects
    recyclerView = getView().findViewById(R.id.recyclerView);
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
    fetchData = new ArrayList<>();


    databaseReference = FirebaseDatabase.getInstance().getReference("subject");
    final ProgressBar progressBar = getView().findViewById(R.id.progressBar);
    progressBar.setVisibility(View.VISIBLE);
    databaseReference.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for (DataSnapshot ds:dataSnapshot.getChildren()){
                FetchDatadata = ds.getValue(FetchData.class);
                fetchData.add(data);
                progressBar.setVisibility(View.INVISIBLE);
                Toast.makeText(getContext(), "Subjects Successfully Loaded", Toast.LENGTH_SHORT).show();
            }
            helperAdapter = new HelperAdapter(fetchData);
            recyclerView.setAdapter(helperAdapter);
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
        }
    });
}

Subjects Successfully Loaded 正在循环中，它会在显示 10 次后停止

我在public void onViewCreated(View view, Bundle savedInstanceState)上调用fetchTheData()方法

【问题讨论】：

标签： android firebase android-fragments firebase-realtime-database

【解决方案1】：

将 Toast 排除在 for 循环之外：

boolean success = false;
databaseReference.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
        for (DataSnapshot ds:dataSnapshot.getChildren()){
            FetchDatadata = ds.getValue(FetchData.class);
            fetchData.add(data);
            progressBar.setVisibility(View.INVISIBLE);
        success = true;
            
        }
       if(success){
       Toast.makeText(getContext(), "Subjects Successfully Loaded", Toast.LENGTH_SHORT).show();
       success = false}
       
        helperAdapter = new HelperAdapter(fetchData);
        recyclerView.setAdapter(helperAdapter);
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
    }
});

【讨论】：