Question

如何在其他片段中更新ListView？

public class ChooseCS extends FragmentActivity {

final private Context context = this;

private HashMap<String, List<String>> mCitiesStreets = null;

private View rootViewStreetChangeFragment = null;
private SimpleAdapter adapter;

...

private static final int NUM_PAGES = 3;

private ViewPager mPager;

private PagerAdapter mPagerAdapter;

...

和两个片段

public class CityChangeFragment extends Fragment {

和

public class StreetChangeFragment extends Fragment {

...

    mMapDataAdapter.put("streets", fillcities);
        adapter = new SimpleAdapter(
                rootViewStreetChangeFragment.getContext(),
                mMapDataAdapter.get("streets"), R.layout.grid_streets_4_7,
                from, to);
        mDataListViewStreets.setAdapter(adapter);

...

我需要从CityChangeFragment在StreetChangeFragment中更新ListView，我在那里更改数据

Answer 1

您可以使用LocalBroadcastManager来实现此目的。

在你的StreetChangeFragment中写下代码

@Override
public void onCreate(Bundle savedInstanceState) {

...

// Register to receive messages.
// We are registering an observer (mMessageReceiver) to receive Intents
// with actions named "custom-event-name".
LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
  new IntentFilter("custom-event-name"));
}

// Our handler for received Intents. This will be called whenever an Intent
// with an action named "custom-event-name" is broadcasted.
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// Get extra data included in the Intent
String message = intent.getStringExtra("message");
Log.d("receiver", "Got message: " + message);
}
};

@Override
protected void onDestroy() {
// Unregister since the activity is about to be closed.
   LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
super.onDestroy();
}

使用以下方法从CityChangeFragment向StreetChangeFragment发送广播消息

private void sendMessage() {
  Log.d("sender", "Broadcasting message");
  Intent intent = new Intent("custom-event-name");
  // You can also include some extra data.
  intent.putExtra("message", "This is my message!");
  LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}

注意：您可以使用intent传递数据（此处您也可以在listview中更新数据）

您可以查看以下链接，了解有关LocalBroadcastManager的更多信息

https://developer.android.com/reference/android/support/v4/content/LocalBroadcastManager.html

Answer 2

接口是个好主意，这个想法基本上是定义一个接口，让活动实现该接口。

一旦实现了该接口，您就可以在它覆盖的方法中执行任何操作。 Simple Developer Blog有一个很好的教程如何做到这一点。

你需要在片段中声明一个方法，它可以通过从适配器获取片段实例来从活动中执行，如

   Fragment fragment= mPagerAdapter.getItem(int positon);
   ((StreetChangeFragment )).updateList();

在StreetChangeFragment声明方法中

并执行您想要的其他操作，谢谢

你好！我需要一些帮助来更新片段中的LIstView

2 个答案: