Question

这是我的微调器函数，在活动的OnCreate（）中调用初始化微调器和设置适配器数据

  private void spinnerSetting() {
    DataBaseOperations dataBaseOperations = new DataBaseOperations(this);
    spinner = (Spinner) findViewById(R.id.volt_spinner_);

    categories = dataBaseOperations.getInvertersType();
    // Creating adapter for spinner
     dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, categories);

    // Drop down layout style - list view with radio writeNfcBt
    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

    // attaching data adapter to spinner
    spinner.setAdapter(dataAdapter);

    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

            mkvValue = parent.getItemAtPosition(position).toString();
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {

        }
    });
}

当我单击按钮时，从这段代码更新我的列表（类别），它向spinner适配器提供数据然后我调用notifyDataSetChange（）但它没有微调器值，但我的列表（类别）是已更新并具有新值，但微调器显示旧值

List<Inverters> allData = inverter.getData();
DataBaseOperations dataBaseOperations = new DataBaseOperations(AdminPanelActivity.this);
dataBaseOperations.addInvertersNames(allData);
categories.clear();
//dataAdapter.clear();
categories = dataBaseOperations.getInvertersType();
dataAdapter.notifyDataSetChanged();
spinner.setAdapter(dataAdapter);

Answer 1

适配器保存对其构造函数中传递的列表的引用。

categories = dataBaseOperations.getInvertersType();
dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, categories);

dataBaseOperations.getInvertersType()每次调用时都会创建一个新ArrayList，但适配器不会更改其内部引用。
这就是为什么您在调用categories = dataBaseOperations.getInvertersType()后没有看到更改的原因，这是适配器不知道的新列表。

你应该这样做：

List<Inverters> allData = inverter.getData();
DataBaseOperations dataBaseOperations = new DataBaseOperations(AdminPanelActivity.this);
dataBaseOperations.addInvertersNames(allData);
categories.clear();
categories.addAll(dataBaseOperations.getInvertersType());
dataAdapter.notifyDataSetChanged();

我的微调器适配器在调用notifyDataSetUpdate更改时没有更新微调器值

1 个答案: