Android：如何在Fragment中更改ListView项的值？

Question

我创建了一个Fragment，其中包含一个带有多个项目的ListView。根据我的计划，当我点击ListView上的其中一项时，我会移动到另一个Fragment，从中获取数据，替换原始数据并更新ListView。为了实现这一点，我编写了以下代码。

1. Code inside the onCreateView() method

   listAdapter = new AlarmOptionItemListAdapter();
   lvAlarmOptionList = (ListView) view.findViewById(R.id.lvAlarmOptionList);
   initializeListItems();
   lvAlarmOptionList.setAdapter(listAdapter);
   

2. The initializeListItems() method that adds several items to lvAlarmOptionList, the ListView instance.

   private void initializeListItems() {
       itemRepeatAlarm = new TextOnlyItem();
       itemRepeatAlarm.setTitle(getString(R.string.repeat_weekly));
       itemRepeatAlarm.setSubtitle(getString(R.string.never));
       listAdapter.addItem(itemRepeatAlarm);
   
       itemAlarmLock = new TextOnlyItem();
       itemAlarmLock.setTitle(getString(R.string.alarm_lock));
       itemAlarmLock.setSubtitle(getString(R.string.choose_option));
       listAdapter.addItem(itemAlarmLock);
   }
   

3. onActivityResult() method that gets the data from the other Fragment and modify the items on the ListView

   @Override
   public void onActivityResult(int requestCode, int resultCode, Intent data) {
   if(resultCode == RESULT_OK && data != null) {
       switch(requestCode) {
           case CODE_PIN:
               String value = data.getStringExtra(Keys.VALUE);
               if(value != null) {
                   Log.i(ApplicationManager.LOG, "PIN set to " + value);
               }
               break;
   
           case CODE_PASSWORD:
               String password = data.getStringExtra(Keys.VALUE);
               if(password != null) {
                   Log.i(ApplicationManager.LOG, "Password set to " + password);
               }
               break;
   
           case CODE_REPEAT:
               repeatType = data.getIntExtra(Keys.REPEAT_TYPE, 0);
               switch(repeatType) {
                   case Keys.SINGLE:
                   case Keys.PLURAL:
                       Toast.makeText(activity, data.getStringExtra(Keys.REPEAT_MESSAGE), Toast.LENGTH_SHORT).show();
                       itemRepeatAlarm.setSubtitle(getString(R.string.on));
                       listAdapter.notifyDataSetChanged();
                       onResume();
                       break;
   
                   case Keys.NO_REPEAT:
                       Toast.makeText(context, getString(R.string.alarm_will_never_repeat), Toast.LENGTH_SHORT).show();
                       itemRepeatAlarm.setSubtitle(getString(R.string.never));
                       listAdapter.notifyDataSetChanged();
                       onResume();
                       break;
   
                   case Keys.EVERY_DAY:
                       Toast.makeText(context, getString(R.string.alarm_will_repeat_every_day), Toast.LENGTH_SHORT).show();
                       itemRepeatAlarm.setSubtitle(getString(R.string.every_day));
                       listAdapter.notifyDataSetChanged();
                       onResume();
                       break;
               }
               break;
   
           case CODE_PATTERN:
               pattern = data.getStringExtra(Keys.VALUE);
               if(pattern != null) {
                   Log.i(ApplicationManager.LOG, "Pattern set to " + pattern);
               }
               itemAlarmLock.setSubtitle(getString(R.string.pattern));
               listAdapter.notifyDataSetChanged();
               onResume();
               break;
       }
   }
   }
   

4. And finally, the onResume() method

   @Override
   public void onResume() {
       super.onResume();
       if(listAdapter != null) {
           listAdapter.notifyDataSetChanged();
       }
   }
   

我成功地使用onActivityResult()方法从另一个Fragment中获取数据，但是我一直无法刷新ListView中的数据。

- marshallslee

---

你不应该从你的代码中调用 Android 的回调函数（例如 onResume）。 - Divers

Answer 1

在你的onActivityResult中，你正在修改itemRepeatAlarm对象，但它在适配器中不会自动更新。你需要从适配器中获取该对象并设置其值，如下所示：

((TextOnlyItem) listAdapter.getItem(0)).setSubtitle(getString(R.string.on);
listAdapter.notifyDataSetChanged();

希望这个有效。

- Hristo Stoyanov

Answer 2

我认为你的问题在于onCreateView在onActivityResult之后执行，因此你的项目将会被重新创建并带有旧的值。 尝试使用以下代码或类似的代码：

private void initializeListItems() {
    if (null == itemRepeatAlarm) {
       itemRepeatAlarm = new TextOnlyItem();
       itemRepeatAlarm.setTitle(getString(R.string.repeat_weekly));
       itemRepeatAlarm.setSubtitle(getString(R.string.never));
       listAdapter.addItem(itemRepeatAlarm);
    }

    if (null == itemAlarmLock) {
        itemAlarmLock = new TextOnlyItem();
        itemAlarmLock.setTitle(getString(R.string.alarm_lock));
        itemAlarmLock.setSubtitle(getString(R.string.choose_option));
        listAdapter.addItem(itemAlarmLock);
    }
}

- firegloves