Question

该应用通过OnDataChange从Firebase获取数组列表，并且OnItemSelected，但不幸的是它不会调用。（实际上，微调器从Firebase数据库获取字符串。）我已经使用本地arraylist和OnItemSelected测试了代码。为什么呢？

这些是我的功能：

        public void initSpinner() {

        restartAudioSpinner();


        try {
            Thread.sleep(4000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(AddAudioItems.this, android.R.layout.simple_spinner_dropdown_item, categoriesTitle);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);

    }




   public void restartAudioSpinner() {
        DatabaseReference database;
        database = FirebaseDatabase.getInstance().getReference("Audio Categories");

        database.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                categorylist = new ArrayList<String>();

                for (DataSnapshot data :dataSnapshot.getChildren()) {
                    CategoryNew category = data.getValue(CategoryNew.class);
                    categoriesList.add(new CategoryNew(category.getImageUrl(),category.getTitle()));
                }

                for (int i = 0; i < categoriesList.size(); i++) {
                    categoriesTitle.add(categoriesList.get(i).getTitle());
                }

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
    }

    @Override
    public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
        Toast.makeText(AddAudioItems.this, categoriesTitle.get(i), Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onNothingSelected(AdapterView<?> adapterView) {
        Toast.makeText(AddAudioItems.this, "לא נבחרה שום רשומה, אנא בחר קטגוריה", Toast.LENGTH_SHORT).show();

    }

Answer 1

最终我自己找到了答案。 Firebase功能同步工作。我还没有找到改变它的方法 - 以某种方式操纵它。处理从firebase函数接收的数据的答案是在for（在数据库中收集信息）INSIDE onDataChange之后初始化所需的函数。例如：

   public void restartAudioSpinner() {
    DatabaseReference database;
    database = FirebaseDatabase.getInstance().getReference("Audio Categories");

    database.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            categorylist = new ArrayList<String>();

            for (DataSnapshot data :dataSnapshot.getChildren()) {
                CategoryNew category = data.getValue(CategoryNew.class);
                categoriesList.add(new CategoryNew(category.getImageUrl(),category.getTitle()));
            }

            for (int i = 0; i < categoriesList.size(); i++) {
                categoriesTitle.add(categoriesList.get(i).getTitle());
            }
                 **// PUT THE DESIRED FUNCTION HERE!!!** EX: INIT THE SPINNER
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

OnItemSelected当Spinner从Firebase获得arraylist时不会调用

1 个答案: