Method to refresh Fragment content when data changed ( like recall onCreateView)

问题

I have an Activity with a fragment container in layout. 3 different Fragment can be displayed in it. There fragments contains a listview which displays data with custom Adapter i made.

So each list elements is created during onCreateView, after i queried a database to have data.

But sometimes some data may changes in my database, si i would like to redraw/recreate it the Listview.

What would be the best way (i mean the less ressources demanding) to refresh my fragment view ?
Is there a method to recall onCreateView manually ?

回答1:

Detach and attach it with

Fragment currentFragment = getFragmentManager().findFragmentByTag("YourFragmentTag");
FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
fragmentTransaction.detach(currentFragment);
fragmentTransaction.attach(currentFragment);
fragmentTransaction.commit();

or search fragment with

Fragment currentFragment = getActivity().getSupportFragmentManager().findFragmentById(R.id.container);

回答2:

There is one very useful method of Fragment, which can be used for refreshing fragment.

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
        //Write down your refresh code here, it will call every time user come to this fragment. 
       //If you are using listview with custom adapter, just call notifyDataSetChanged(). 
    }
}

回答3:

Combined two answers and removed if (isVisibleToUser), because it makes the setUserVisibleHint be called in an unpredicted asynchroneous order and fragment can either be refreshed or not. I found this piece of code stable (in your Fragment):

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {

super.setUserVisibleHint(isVisibleToUser);

  // Refresh tab data:

  if (getFragmentManager() != null) {

    getFragmentManager()
      .beginTransaction()
      .detach(this)
      .attach(this)
      .commit();
  }
}

回答4:

If you have problems with some of the methods listed above (as I had after uprgrading...), I recommend to make some kind of public refresh method in fragment and then simply call it, it is even less code, nicer and faster because fragment doesn't need to be reinitialized...

FragmentManager fm = getSupportFragmentManager();

//if you added fragment via layout xml
Fragment fragment = fm.findFragmentById(R.id.your_fragment_id);
if(fragment instanceof YourFragmentClass) // avoid crash if cast fail
{
    ((YourFragmentClass)fragment).showPrayer();
}

If you added fragment via code and used a tag string when you added your fragment, use findFragmentByTag instead:

Fragment fragment = fm.findFragmentByTag("yourTag");
if(fragment instanceof YourFragmentClass)
{
    ((YourFragmentClass)fragment).showPrayer();
}

回答5:

When the data in a fragment changes, its always a good idea to detach and reattach the fragment into the framelayout. In my case, I have a listview which shows the favorite items of my users. Once the user unlike a product, I have to remove it from the list and reload the Favorites fragment.

So I did something like this to reload the fragment into the frame layout:

FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.frm,new FavoritesFragment()).addToBackStack(null).commit();

Here, frm is the frame layout in the MainActivity that hold the fragment and FavoritesFragment() is the fragment that needs to be reloaded.

The above code should be executed everytime the user press unlike button

回答6:

According to FragmentTransaction#replace it's the same as calling remove and then add. So you can use .replace with the fragment manager when you're starting the fragment or when you want to reload it. So use the same function from the onCreate as well as the place where you'd want to reload it...

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

    if (savedInstanceState == null) {
        loadContentFragment();
    }
}

private void someFunctionThatChangesValue(String value) {
    mValue = value;
    loadContentFragment();
}

private void loadContentFragment() {
    ContentListFragment newFrag = ContentListFragment.newInstance();
    // passing value from activity
    Bundle args = new Bundle();
    args.putString(Constants.ARG_ACCOUNT_NAME, mValue);
    newFrag.setArguments(args);
    getSupportFragmentManager().beginTransaction()
            .replace(R.id.content_frag_container,
                    newFrag,
                    Constants.CONTENT_FRAGMENT)
            .commitNow();
}

This way there's only one function that loads the content and passes data. This assumes you have an entry in your layout with the ID content_frag_container. I used a FrameLayout.

回答7:

This method works for me:

MyCameraFragment f2 = new MyCameraFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.frame_container, f2);
transaction.addToBackStack(null);
transaction.commit();

回答8:

Following code refreshes A fragment from withIn an Adapter

DownloadsAdapter code:

public class DownloadsAdapter extends RecyclerView.Adapter<DownloadsAdapter.ViewHolder> {

private Context mCtx;

//getting the context and product list with constructor
public DownloadsAdapter(Context mCtx, List<DataModel> fileUrlLinkList) {
    this.mCtx = mCtx;
    this.fileUrlList = fileUrlLinkList;

}

**... and in onBindViewHolder**

 FragmentManager manager = ((AppCompatActivity) mCtx).getSupportFragmentManager();
 Fragment currentFragment = manager.findFragmentByTag("DOWNLOADS");
 FragmentTransaction fragmentTransaction = manager.beginTransaction();
 fragmentTransaction.detach(currentFragment);
 fragmentTransaction.attach(currentFragment);
 fragmentTransaction.commit();

...

}

来源：https://stackoverflow.com/questions/32359727/method-to-refresh-fragment-content-when-data-changed-like-recall-oncreateview

标签

android

listview

android-fragments

fragment

refresh