如何从viewpager android刷新或更新所有片段

Question

我有带有 tablayout 的 viewpager，里面有 3 个片段。在我的片段 2 和 3 中，我滑动以刷新以更新 firebase 数据库中的数据。

我希望它使用工具栏中的 1 个按钮刷新，并刷新其中的所有片段。

还有一个问题是，我必须刷新片段 2 次才能更新 recyclerview ..... 不知道怎么弄，请帮忙

双片段

public static final String TAG = "TWO_FRAGMENT";

@Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);

        if (isVisibleToUser) {

        } else {
            mAuth = FirebaseAuth.getInstance();
            userRef = FirebaseDatabase.getInstance().getReference("user_course");
            users = FirebaseAuth.getInstance().getCurrentUser();
            daftarTugasRef = FirebaseDatabase.getInstance().getReference("tugas");
            mTugasRef = FirebaseDatabase.getInstance().getReference("tugas_course");
            mFlagTugas = FirebaseDatabase.getInstance().getReference("flag_tugas");

            LoadData();
        }
    }


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    setHasOptionsMenu(true);

    v =  inflater.inflate(R.layout.fragment_two, container, false);

swipeLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                new Handler().postDelayed(new Runnable() {

                    @Override public void run() {
                        LoadData();
                        swipeLayout.setRefreshing(false);
                        listTugas.clear();

                    }
                    private void onLoaded() {
                        swipeLayout.setEnabled(true);
                        swipeLayout.setRefreshing(false);
                    }

                }, 500);
            }
        });

MainActivity

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

       viewPager = (ViewPager) findViewById(R.id.viewpager);
        viewPager.setOffscreenPageLimit(3);
        setupViewPager(viewPager);
        viewPager.setCurrentItem(position);
        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
reloadFragment("TWO_FRAGMENT");

        setupTabIcons();
}

private void setupViewPager(ViewPager viewPager) {
        adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFrag(new OneFragment(), "ONE");
        adapter.addFrag(new TwoFragment(), "TWO");
        adapter.addFrag(new ThreeFragment(), "THREE");
        viewPager.setAdapter(adapter);
        viewPager.getAdapter().notifyDataSetChanged();
    }




    class ViewPagerAdapter extends FragmentStatePagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }



        public void addFrag(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

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

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

    }




    @Override
    public void onPageSelected(int position) {
//        viewPager.getAdapter().notifyDataSetChanged();

//        adapter.notifyDataSetChanged();
    }

    @Override
    public void onPageScrollStateChanged(int state) {

    }

protected void reloadFragment(String TAG){
        // Reload current fragment
        Fragment frg = null;
        frg = this.getSupportFragmentManager().findFragmentByTag(TAG);
        FragmentTransaction ft =this.getSupportFragmentManager().beginTransaction();
        ft.detach(frg);
        ft.attach(frg);
        ft.commit();
    }

Answer 1

你可以使用EventBus，把它放在你所有的片段中：

 @Override
 public void onStart() {
     super.onStart();
     EventBus.getDefault().register(this);
 }

 @Override
 public void onStop() {
     super.onStop();
     EventBus.getDefault().unregister(this);
 }


@Subscribe(threadMode = ThreadMode.MAIN)
    public void onEvent(ViewEvent viewEvent) {
        if (viewEvent.getMessage().equals("updateViews")) {
            updateView();

        }


    }

当你想更新时，你可以发送这样的事件：

 EventBus.getDefault().post(new ViewEvent("updateViews"));

PS：ViewEvent 是一个您必须创建的对象，其中包含要发送给所有订阅片段的内容。

public class ViewEvent {

    private String message;

    public ViewEvent( String message) {

        this.message = message;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

Answer 2

只需在您的按钮单击上调用以下方法即可刷新片段 -

 protected void reloadFragment(String TAG){
        // Reload current fragment
        Fragment frg = null;
        frg = getActivity().getSupportFragmentManager().findFragmentByTag(TAG);
        FragmentTransaction ft = getActivity().getSupportFragmentManager().beginTransaction();
        ft.detach(frg);
        ft.attach(frg);
        ft.commit();
    }

通过以下代码行在 Fragment 中声明您的 TAG 变量 -

public static final String TAG = "HOME_FRAGMENT";

每当您在活动中推送片段时，请使用相同的标签 -

getSupportFragmentManager().beginTransaction().setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out, android.R.anim.fade_in, android.R.anim.fade_out).replace(container, fragment, tag).commit();

您只需要为每个 Fragment 设置一个 TAG。希望你能得到使用这个的解决方案。