来自活动的刷新片段

Question

我正在使用一个主要活动来显示不同的片段。我需要根据广播结果刷新片段之一。我提到的内容如下。

我的片段类：

public class ConservationFragment extends Fragment
{
FragmentType fragmentType;

private RecyclerView recyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager layoutManager;

public ConservationFragment()
{
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
}

@Override
public void onResume()
{
    super.onResume();
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
    View rootView = inflater.inflate(R.layout.fragment_conservation, container, false);
    try
    {
        this.fragmentType = (FragmentType) getArguments().getSerializable("fragmenttype");
        ArrayList<Message> messageRecords = getMessagesFromDB(fragmentType);

        recyclerView = (RecyclerView) rootView.findViewById(R.id.conservationsRecyclerView);
        recyclerView.setHasFixedSize(true);

        layoutManager = new LinearLayoutManager(getActivity());
        recyclerView.setLayoutManager(layoutManager);

        mAdapter = new ConversationAdapter(messageRecords, getActivity());
        recyclerView.setAdapter(mAdapter);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        return rootView;
    } catch (Exception e)
    {
        Log.d("RUNTIME ERROR", "Please check ConversationFragment's onCreateView method.");
    }

    return inflater.inflate(R.layout.fragment_conservation, container, false);
}


public ArrayList<Message> getMessagesFromDB(FragmentType fragmentType)
{
    ..
}
}

我如何在主要活动中启动片段；

public class MainActivity extends AppCompatActivity
{

//This is our tablayout
private TabLayout tabLayout;

//This is our viewPager
private ViewPager viewPager;

ConservationFragment personalFragment;
ConservationFragment blockedFragment;

SmsReceiver receiver;

ViewPagerAdapter adapter;


String[] tabTitle = {"PERSONAL", "BLOCKED"}; //
int[] unreadCount = {1, 2};

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

    receiver = new SmsReceiver();
    IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction("android.provider.Telephony.SMS_RECEIVED");
    registerReceiver(receiver, intentFilter);
}
@Override
protected void onResume()
{
    super.onResume();

    //Initializing viewPager
    viewPager = (ViewPager) findViewById(R.id.viewpager);

    setupViewPager(viewPager);

    //Initializing the tablayout
    tabLayout = (TabLayout) findViewById(R.id.tablayout);
    tabLayout.setupWithViewPager(viewPager);

    try
    {
        setupTabIcons();
    } catch (Exception e)
    {
        e.printStackTrace();
    }


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

        }

        @Override
        public void onPageSelected(int position)
        {
            viewPager.setCurrentItem(position, false);
        }

        @Override
        public void onPageScrollStateChanged(int state)
        {

        }
    });

}

private void setupViewPager(ViewPager viewPager)
{
    Bundle personalCriterial= new Bundle();
    personalCriterial.putSerializable("fragmenttype",FragmentType.PERSONAL);
    Bundle blockedCriterial= new Bundle();
    blockedCriterial.putSerializable("fragmenttype",FragmentType.BLOCKED);

    adapter = new ViewPagerAdapter(getSupportFragmentManager());

    personalFragment = new ConservationFragment();
    personalFragment.setArguments(personalCriterial);
    blockedFragment = new ConservationFragment();
    blockedFragment.setArguments(blockedCriterial);

    adapter.addFragment(personalFragment, tabTitle[0]);
    adapter.addFragment(blockedFragment, tabTitle[1]);
    viewPager.setAdapter(adapter);
}

private void setupTabIcons()
{
    for (int i = 0; i < tabTitle.length; i++)
    {
        tabLayout.getTabAt(i).setCustomView(prepareTabView(i));
    }
}

private View prepareTabView(int pos)
{
    View view = getLayoutInflater().inflate(R.layout.custom_tab, null);
    TextView tv_title = (TextView) view.findViewById(R.id.tv_title);
    TextView tv_count = (TextView) view.findViewById(R.id.tv_count);
    tv_title.setText(tabTitle[pos]);
    return view;
}

public void receiveMessage(Intent intent)
{
    //here I want to refresh one of my fragments. such as personalFragment..
}

}

关键点在这里；选项卡视图不应进入第一个选项卡。（更新应在同一片段中） 我知道代码很长，但我必须展示我如何启动对象来引导解决方案。谢谢。

Answer 1

如果你不需要更新整个fragment，而只是传递一些数据和刷新textviews或lists，你总是可以在fragment中定义公共方法并从activity中调用它。

片段中的示例方法：

public void updateWithData(String exampleString) {
    myTextView.setText(exampleString);
}

活动中的使用示例：

public void receiveMessage(Intent intent) {
    myFragment.updateWithDate("Example string message");
}

这样，您不需要重新创建整个片段，而可以只更新相关的 UI 元素。但是，请记住，当您调用此更新方法时，您需要确保片段已创建并显示，否则您将获得未定义的行为。

PS：创建类似 Updatable 接口并在您的片段中实现它可能是一个好主意，这样您就可以在应用程序的其他地方重用此更新逻辑。但这不是必需的，对于小范围，公共方法应该足够了。