Android微调器 - 刷新后禁止关闭

Question

我有一个显示项目列表的下拉微调器，此列表在接收到API响应后每隔X秒更新一次。

问题是，当列表更新时，微调器会自动关闭。我希望它在刷新后保持打开状态。

private void getItems(JSONArray j){ 
    ArrayList<String> items = new ArrayList<>(); 

    for (int i=0; i < j.length(); i++){ 
     try { 
      //Getting json object 
      JSONObject json = j.getJSONObject(i); 

      //Adding the name of the student to array list 
      items.add(json.getString("name")); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
    } 
    spinner.setAdapter(new ArrayAdapter<>(BaseActivity.this, android.R.layout.simple_spinner_dropdown_item, items)); 
} 

Answer 1

这是一个演示，显示如何在保持打开的同时更新Spinner。

首先使用setAdapter设置adapter来初始化Spinner。

然后对项目进行更新。我用Handler来模仿更新。在getItems方法的内部，而不是创建新的适配器（使用notifyDataSetChanged）来通知适配器数据集已更改。

下面的代码。

private Spinner spinner; 
private ArrayAdapter<String> adapter; 
final List<String> items = new ArrayList<>(); 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_test); 

    initializeSpinner(); 
    new Handler().postDelayed(new Runnable() { 
     @Override 
     public void run() { 
      try { 
       String updatedItems = "[{\"name\" : \"test1\"}, {\"name\" : \"test2\"}, {\"name\" : \"test2\"}]"; 
       getItems(new JSONArray(updatedItems)); 
      } catch (JSONException e) { 
       e.printStackTrace(); 
      } 
     } 
    }, 10000); 

} 


private void initializeSpinner() { 
    items.add("initial"); 

    spinner = (Spinner) findViewById(R.id.spinner); 
    adapter = new ArrayAdapter<String>(TestActivity.this, android.R.layout.simple_spinner_dropdown_item, items); 
    spinner.setAdapter(adapter); 
} 

private void getItems(JSONArray j) { 
    for (int i = 0; i < j.length(); i++) { 
     try { 
      //Getting json object 
      JSONObject json = j.getJSONObject(i); 

      //Adding the name of the student to array list 
      items.add(json.getString("name")); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
    } 

    adapter.notifyDataSetChanged(); 
} 

Answer 2

实际上，您只需要初始化并将适配器添加到微调器中。然后加载数据，将数据添加到适配器并调用adapter.notifyDataSetChanged（）;

这里是我的测试活动，您可以直接复制粘贴到你的活动

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    LinearLayout linearLayout = new LinearLayout(this); 
    linearLayout.setOrientation(LinearLayout.VERTICAL); 
    linearLayout.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); 
    setContentView(linearLayout); 

    Spinner spinner = new Spinner(this); 
    adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, new ArrayList<String>()); 
    spinner.setAdapter(adapter); 

    Button button = new Button(this); 
    button.setText("load data"); 
    button.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      TestActivity.this.getWindow().getDecorView().getHandler().postDelayed(new Runnable() { 
       @Override 
       public void run() { 
        loadData(); 
       } 
      }, 2000); 
     } 
    }); 

    linearLayout.addView(spinner); 
    linearLayout.addView(button); 
} 

private void loadData() { 
    String jsonArray = "[\n" + 
      " {\n" + 
      " \"id\": \"1\",\n" + 
      " \"name\": \"dada1\"\n" + 
      " },\n" + 
      " {\n" + 
      " \"id\": \"2\",\n" + 
      " \"name\": \"dada2\"\n" + 
      " },\n" + 
      " {\n" + 
      " \"id\": \"3\",\n" + 
      " \"name\": \"dada3\"\n" + 
      " },\n" + 
      " {\n" + 
      " \"id\": \"4\",\n" + 
      " \"name\": \"dada4\"\n" + 
      " },\n" + 
      " \n" + 
      "]"; 
    try { 
     getItems(new JSONArray(jsonArray)); 
    } catch (JSONException e) { 
     e.printStackTrace(); 
    } 
} 

private ArrayAdapter<String> adapter; 

private void getItems(JSONArray j) { 
    ArrayList<String> items = new ArrayList<>(); 

    for (int i = 0; i < j.length(); i++) { 
     try { 
      //Getting json object 
      JSONObject json = j.getJSONObject(i); 

      //Adding the name of the student to array list 
      items.add(json.getString("name")); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
    } 
    adapter.addAll(items); 
    adapter.notifyDataSetChanged(); 
} 

如何检验呢？

• 运行活动
• 按
• 2秒钟后，您的项目产生
• 再次按下按钮，该按钮并按下微调立即
• 您将看到的项目是不收加2秒后弹出