Question

我有一个膨胀xml布局的片段。我的要求是在恢复活动时更新片段内所有视图的文本大小。我试过了

    fragment.getView().invalidate();

似乎没有做这项工作。我也试过

    fragment.getView().requestLayout();

也不起作用。

在另一个活动中，我有一个需要做同样事情的ListFragment。我试过了

    listfragment.getListView().invalidate();

完成了这个技巧，刷新了我的列表视图并重新绘制了其中的所有项目。

我不明白为什么一个有效而另一个无效。

我也看到人们建议启动片段事务并用新的片段替换当前片段，这让我感到疑惑

为什么我需要创建一个全新的片段并替换当前片段，只需刷新片段所包含的视图上的文本。
片段事务方法会阻止我在我的活动的布局xml中定义我的片段，我将不得不以编程方式将片段插入到正确的位置。

这有什么简单的方法吗？

Answer 1

我认为没有办法解决这个问题。片段在onCreateView（）上重建它的UI ...但是在创建或重新创建片段时会发生这种情况。

您必须实现自己的updateUI方法，或者您将指定哪些元素及其更新方式。这是一个很好的做法，因为无论如何你都需要在创建片段时这样做。

然而，如果这还不够，你可以做一些事情，比如用同一个片段替换片段，强迫它调用onCreateView()

FragmentTransaction tr = getFragmentManager().beginTransaction();
tr.replace(R.id.your_fragment_container, yourFragmentInstance);
tr.commit()

注意

要刷新ListView，您需要在ListView的适配器上调用notifyDataSetChanged()。

Answer 2

就我而言，detach和attach适合我。

 getSupportFragmentManager()
                .beginTransaction()
                .detach(contentFragment)
                .attach(contentFragment)
                .commit();

Answer 3

使用以下代码重新刷新片段：

FragmentTransaction ftr = getFragmentManager().beginTransaction();                          
ftr.detach(EnterYourFragmentName.this).attach(EnterYourFragmentName.this).commit();

Answer 4

支持库更新25.1.0之后

detach().detach()无效（可能更早）。更新后此解决方案正常工作：

getSupportFragmentManager()
    .beginTransaction()
    .detach(oldFragment)
    .commitNowAllowingStateLoss();

getSupportFragmentManager()
    .beginTransaction()
    .attach(oldFragment)
    .commitAllowingStateLoss();

Answer 5

要解决这个问题，我用这个：

Fragment frg = null;
frg = getFragmentManager().findFragmentByTag("Feedback");
final android.support.v4.app.FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.detach(frg);
ft.attach(frg);
ft.commit();

Answer 6

这在片段中对我有用：

Fragment frg = null;
Class fragmentClass;
fragmentClass = MainFragment.class;

try {
    frg = (android.support.v4.app.Fragment)     
    fragmentClass.newInstance();
} catch(Exception ex) {
    ex.printStackTrace();
}

getFragmentManager()
    .beginTransaction()
    .replace(R.id.flContent, frg)
    .commit();

Answer 7

我正在使用删除和替换两者来刷新片段的内容，如

final FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.remove(resetFragment).commit();
fragmentTransaction.replace(R.id.frame_container,resetFragment).commit();

Answer 8

让我们看看下面的源代码。这里的片段名称是DirectoryOfEbooks。完成后台任务后，我用当前片段替换帧。所以片段得到刷新并重新加载其数据

    import android.app.ProgressDialog;
    import android.content.DialogInterface;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentTransaction;
    import android.support.v4.view.MenuItemCompat;
    import android.support.v7.app.AlertDialog;
    import android.support.v7.widget.DefaultItemAnimator;
    import android.support.v7.widget.GridLayoutManager;
    import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;
    import android.support.v7.widget.SearchView;
    import android.view.LayoutInflater;
    import android.view.Menu;
    import android.view.MenuInflater;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    import android.widget.Toast;

    import com.github.mikephil.charting.data.LineRadarDataSet;

    import java.util.ArrayList;
    import java.util.List;


    /**
     * A simple {@link Fragment} subclass.
     */
    public class DirectoryOfEbooks extends Fragment {

        RecyclerView recyclerView;
        branchesAdapter adapter;
        LinearLayoutManager linearLayoutManager;
        Cursor c;
        FragmentTransaction fragmentTransaction;
        SQLiteDatabase db;
        List<branch_sync> directoryarraylist;

        public DirectoryOfEbooks() {
            // Required empty public constructor
        }
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {


            View view = inflater.inflate(R.layout.fragment_directory_of_ebooks, container, false);
            directoryarraylist = new ArrayList<>();
            db = getActivity().openOrCreateDatabase("notify", android.content.Context.MODE_PRIVATE, null);
            c = db.rawQuery("select * FROM branch; ", null);

            if (c.getCount() != 0) {
                c.moveToFirst();
                while (true) {
                    //String ISBN = c.getString(c.getColumnIndex("ISBN"));
                    String branch = c.getString(c.getColumnIndex("branch"));

                    branch_sync branchSync = new branch_sync(branch);
                    directoryarraylist.add(branchSync);
                    if (c.isLast())
                        break;
                    else
                        c.moveToNext();
                }

                recyclerView = (RecyclerView) view.findViewById(R.id.directoryOfEbooks);
                adapter = new branchesAdapter(directoryarraylist, this.getContext());
                adapter.setHasStableIds(true);
                recyclerView.setItemAnimator(new DefaultItemAnimator());
                System.out.println("ebooks");
                recyclerView.setHasFixedSize(true);
                linearLayoutManager = new LinearLayoutManager(this.getContext());
                recyclerView.setLayoutManager(linearLayoutManager);
                recyclerView.setAdapter(adapter);
                System.out.println(adapter.getItemCount()+"adpater count");

            }
            // Inflate the layout for this fragment
            return view;
        }
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            //setContentView(R.layout.fragment_books);
            setHasOptionsMenu(true);
        }
        public void onPrepareOptionsMenu(Menu menu) {
            MenuInflater inflater = getActivity().getMenuInflater();
            inflater.inflate(R.menu.refresh, menu);
            MenuItem menuItem = menu.findItem(R.id.refresh1);
            menuItem.setVisible(true);
        }
        public boolean onOptionsItemSelected(MenuItem item) {
            if (item.getItemId() == R.id.refresh1) {
                new AlertDialog.Builder(getContext()).setMessage("Refresh takes more than a Minute").setPositiveButton("Refresh Now", new DialogInterface.OnClickListener() {

                    public void onClick(DialogInterface dialog, int which) {

                        new refreshebooks().execute();
                    }
                }).setNegativeButton("Refresh Later", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {

                    }
                }).setCancelable(false).show();

            }
            return super.onOptionsItemSelected(item);
        }

    public class refreshebooks extends AsyncTask<String,String,String>{
        ProgressDialog progressDialog;
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
          progressDialog=new ProgressDialog(getContext());
            progressDialog.setMessage("\tRefreshing Ebooks .....");
            progressDialog.setCancelable(false);
            progressDialog.show();
        }

        @Override
        protected String doInBackground(String... params) {
            Ebooksync syncEbooks=new Ebooksync();
            String status=syncEbooks.syncdata(getContext());
            return status;

        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            if(s.equals("error")){
                progressDialog.dismiss();
                Toast.makeText(getContext(),"Refresh Failed",Toast.LENGTH_SHORT).show();
            }
            else{
                fragmentTransaction = getActivity().getSupportFragmentManager().beginTransaction();
                fragmentTransaction.replace(R.id.mainframe, new DirectoryOfEbooks());
                fragmentTransaction.commit();
                progressDialog.dismiss();
                adapter.notifyDataSetChanged();
                Toast.makeText(getContext(),"Refresh Successfull",Toast.LENGTH_SHORT).show();
            }

        }
    }

    }

刷新或强制重绘片段

8 个答案: