在 FragmentActivity 中刷新 Fragment

Question

我的应用程序有一个带 tabBar 的 fragmentActivity，它控制视图寻呼机并包含 3 个片段，当我在 fragmentB 中更新我的 class User 时，我需要将他显示在fragmentC。我的问题是每次添加新用户时如何刷新 fragmentC。

在我写这个问题之前，我尝试了这个问题的所有解决方案：

1.Update ViewPager dynamically?

2.refresh fragment at reload

3.Update Fragment from ViewPager

4.ViewPager PagerAdapter not updating the View

5.How to update fragment content from activity (viewpager)?

这是我的代码

片段活动：

public class MainActivityTab extends FragmentActivity  {


    public SectionsPagerAdapter mSectionsPagerAdapter;
    public ViewPager mViewPager;
    public static MainActivityTab instance = null;


    public static MainActivityTab getInstance(){
        return instance;
    }

    @Override
    protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_tab);
        getWindow().setStatusBarColor(Color.rgb(191,76,12));
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);
        final TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);
        tabLayout.getTabAt(0).setIcon(R.drawable.icon_A);
        tabLayout.getTabAt(1).setIcon(R.drawable.icon_B);
        tabLayout.getTabAt(2).setIcon(R.drawable.icon_C);
        mViewPager.setCurrentItem(1,false);
    }

FragmentStatePagerAdapter:

 public class SectionsPagerAdapter extends FragmentStatePagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            switch (position){
                case 0:
                    return FragmentA.newInstance();
                case 1:
                    return FragmentA.newInstance();
                case 2:
                    return FragmentC.newInstance();
                default:
                    return null;
            }
        }

        @Override
        public int getItemPosition(Object object) {
            return POSITION_NONE;
        }

        @Override
        public int getCount() {
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return null;
        }
    }

片段B:

public class FragmentB extends Fragment {

    EditText name;
    EditText age;
    Button btnSave;

    public static FragmentB newInstance() {
        FragmentB fragment = new FragmentB();
        return fragment;
    }
    public FragmentB() {}

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_new2, container, false);
        name = (EditText) rootView.findViewById(R.id.name);
        age = (EditText) rootView.findViewById(R.id.age);
        btnSave = (Button) rootView.findViewById(R.id.btnSave);
        btnSave.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                UserManager.getInstance().creteUser(name.getText().toString(),age.getText().toString());
            }
        });
        return rootView;
    }
}

片段C:

public class FragmentC extends Fragment {
    TextView nameTxt;
    TextView ageTxt;

    public static FragmentC newInstance(){
        FragmentC instance = new FragmentC();
        return instance;
    }
    public FragmentC(){

    }
@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
     View rootView = inflater.inflate(R.layout.fragment_new3, container, false);
    nameTxt = (TextView) rootView.findViewById(R.id.nameTxt);
    ageTxt = (TextView) rootView.findViewById(R.id.ageTxt);
    showUser();
    return rootView;
    }
    public void showUser(){

        if(UserManager.getInstance().getUser().getName()!=null){
            nameTxt.setText(UserManager.getInstance().getUser().getName().toString());
            ageTxt.setText(UserManager.getInstance().getUser().getAge().toString());
        }
    }

}

Answer 1

您可以像这样创建回调：

public interface UserChangedCallback{
  void onUserChanged();
}

并在您想要访问用户的每个 view/fragment 上实施此回调：

@Override
public void onUserChanged() {
  adapter.notifyDataSetChanged();
  // or if you don't have an adapter refresh your textfields or whatever you want
}

通过UserManager.getInstance().registerCallback(this)在用户管理器上注册回调。在内部，用户管理器必须将回调添加到内部列表。

在您的用户管理器中创建一个私有函数：

private void notifyCallbacks() {
  for(UserChangedCallback callback : registeredCallbacks) {
    callback.onUserChanged();
  } 
}

如果您 add/modify/delete 是用户，您总是必须在最后调用此函数。例如：

public void addUser(User user) {
  users.add(user);
  notifiCallbacks();
}

现在每个视图都会收到通知并刷新。

重要！

不要忘记在 onDestroy() 上从用户管理器注销回调以避免内存泄漏。

Answer 2

找到解决方案：

我在方法 onPageSelected 中使用，当位置为 2 时，我的片段分离，然后附加片段。完美运行！

mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
                @Override
                public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

                }

                @Override
                public void onPageSelected(int position) {
                    if(position==2){
                        FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction().add(R.id.fragmant_new3, FragmentC.newInstance());
                        fragmentTransaction.detach(FragmentC.newInstance());
                        fragmentTransaction.attach(FragmentC.newInstance());
                        fragmentTransaction.commit();

                    }
                }

                @Override
                public void onPageScrollStateChanged(int state) {

                }
            });

在 FragmentActivity 中刷新 Fragment

Refresh Fragment in FragmentActivity

android

android-fragments

android-fragmentactivity