Question

我使用翻新，显示的项目，但我无法选择。单击项目后，吐司和微调器什么都没有显示（我无法在微调器上选择项目）。......

    <div class="main">

        <section class="signup">
            <div class="container">
                <div class="row">
                <div class="signup-content col-sm-12">
                    <form id="signup-form" class="signup-form" method="post" action="{% url 'login' %}">
                        {% csrf_token %}
                        <h2 class="form-title">Log In</h2>
                            {{ form | crispy}}
                            <input type="submit" style="margin-top: 10px" value="Login" class="button" id="" />
                            <input type="hidden" name="next" value="{{ next }}" />
                    </form>
                    <div class="col-sm-12" style="text-align: right; margin-top: 5px">
                        <a href="{% url 'password_reset' %}">Forgot Password?</a>

                    </div>
                    <p class="loginhere">
                        New Here ? <a href="/account/register" class="loginhere-link">Create an account here</a>
                    </p>
                </div>
            </div>
                </div>
        </section>

    </div>

Answer 1

当前解决方案：

您在setSpinner()中为适配器设置了名为spinnerItem的列表，该列表目前为空。然后在displayCities()中用值填充列表，但是忘记将添加的新值通知适配器。

public void displayCities(List<CityResponse.City> cities) {
        for (CityResponse.City city : cities) {
            spinnerItem.add(city.getNama());
        }
        // 2. notify adapter that you have inserted new cities to the list
}

private void setSpinner(){
        // 1. set the adapter with spinnerItem which is empty here
        ArrayAdapter<String> adapter = new ArrayAdapter<>(..., ..., spinnerItem);
        mainBinding.spinnerCity.setAdapter(adapter);
        ...
}

如果adapter是setSpinner()的局部变量，则displayCities()无权访问adapter。将adapter创建为全局变量，然后可以在第2点注释中调用adapter.notiftDataSetChanged()

Answer 2

您的setSpinner（）方法：

private void setSpinner(final Context context, Spinner spinnerCity, List<Object> spinnerItem) {
    final ArrayAdapter adapter = new ArrayAdapter(context, android.R.layout.simple_spinner_item, spinnerItem);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinnerCity.setAdapter(adapter);
    spinnerCity.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            String citySelected = parent.getItemAtPosition(position).toString();
            //adapter.notifyDataSetChanged();
            Toast.makeText(context, "City : " + citySelected, Toast.LENGTH_LONG).show();
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
            Toast.makeText(context, "Not Selected", Toast.LENGTH_LONG).show();
        }
    });
}

CityActivity.java：

Spinner spinnerCity = findViewById(R.id.spinner);
String[] spinnerItem = {"A", "B", "C", "D", "E"};
setSpinner(CityActivity.this, spinnerCity, Arrays.<Object>asList(spinnerItem));

如何选择微调器上的项目？

2 个答案: