从活动更新片段

Question

我不明白如何将数据从 FragmentActivity 传输到 Fragment，我有：

MainScreen.class

public class MainScreen extends FragmentActivity {
CollectionPagerAdapter mCollectionPagerAdapter;
ViewPager mViewPager;

public static String currentCityId;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.tabs_collection);

    mCollectionPagerAdapter = new CollectionPagerAdapter(getSupportFragmentManager());

    final ActionBar actionBar = getActionBar();

    actionBar.setDisplayHomeAsUpEnabled(false);
    actionBar.setTitle(getString(R.string.app_name));
    actionBar.setIcon(R.drawable.device_access_brightness_high);

    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mCollectionPagerAdapter);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.mainmenu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.action_refresh:
            Log.w("Refresh", "refresh");

            break;
        case R.id.action_options:

            break;
        case R.id.submenu_about:

            break;
        case R.id.submenu_help:

            break;
        case R.id.submenu_buy:

            break;
        case R.id.submenu_settings:

            break;
        case R.id.submenu_share:

            break;
        default:
            break;
    }

    return true;
}

public class CollectionPagerAdapter extends FragmentStatePagerAdapter {
    FragmentManager fm;

    public CollectionPagerAdapter(FragmentManager fm) {
        super(fm);
        this.fm = fm;
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new FragmentDay();
            case 1:
                return new FragmentHour();
            case 2:
                return new FragmentDaily();
            default:
                return new FragmentDay();
        }
    }

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

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return getString(R.string.tab_day);
            case 1:
                return getString(R.string.tab_hour);
            case 2:
                return getString(R.string.tab_daily);
            default:
                return getString(R.string.tab_day);
        }
    }
}

FragmentDay.class

public class FragmentDay extends Fragment {
TextView currentTemp;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.hour_screen, container, false);
    Bundle args = getArguments();
    currentTemp = (TextView)rootView.findViewById(R.id.day_current_temp);
    return rootView;
}

}

main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
            android:layout_height="match_parent"
            android:layout_width="match_parent"
            android:background="@drawable/bk_new">

<android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    <android.support.v4.view.PagerTitleStrip
            android:id="@+id/pager_title_strip"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="top"
            android:background="#33b5e5"
            android:textColor="#fff"
            android:paddingTop="4dp"
            android:paddingBottom="4dp"/>
</android.support.v4.view.ViewPager>

和fragment.xml：

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/dayScreen"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/bk_new">

<TextView
        android:id="@+id/day_current_temp"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:layout_centerHorizontal="true"
        android:text="22 C"
        android:textColor="#FFFFFF"
        android:textSize="38dp"
        android:layout_marginTop="270dp"/>

看了这些文章（ViewPager Activity to notify a Fragment of a specific event、Updating fragments from Activity in a ViewPager、ViewPager - Update fragment from activity）不明白怎么办！ 我将非常感谢您的帮助！

Answer 1

当您说“传输数据”时，我假设您指的是变量，因此您可以以任何方式调整片段。

您可以随时使用 getActivity() 方法在片段中访问活动对象并将其转换为您的活动实现...

// Code in the fragment
((MainScreen) getActivity()).getSomeDataFromActivity()

Google 也有一篇文章here 描述了 Fragment 和 Activity 之间的通信模式。