Question

我在view pager的文档中看到了这段代码。我想将活动中的字符串传递给片段类。我想我可以使用bundle args传递它。我如何在我的片段类中访问它？也有人可以解释为什么我们在这里扩展片段活动？

public class ActionBarTabsPager extends Activity {
ViewPager mViewPager;
TabsAdapter mTabsAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    mViewPager = new ViewPager(this);
    mViewPager.setId(R.id.pager);
    setContentView(mViewPager);

    final ActionBar bar = getActionBar();
    bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
    bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);

    mTabsAdapter = new TabsAdapter(this, mViewPager);
    mTabsAdapter.addTab(bar.newTab().setText("Simple"),
            CountingFragment.class, null);
    mTabsAdapter.addTab(bar.newTab().setText("List"),
            FragmentPagerSupport.ArrayListFragment.class, null);
    mTabsAdapter.addTab(bar.newTab().setText("Cursor"),
            CursorFragment.class, null);

    if (savedInstanceState != null) {
        bar.setSelectedNavigationItem(savedInstanceState.getInt("tab", 0));
    }
}

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putInt("tab", getActionBar().getSelectedNavigationIndex());
}

/**
 * This is a helper class that implements the management of tabs and all
 * details of connecting a ViewPager with associated TabHost.  It relies on a
 * trick.  Normally a tab host has a simple API for supplying a View or
 * Intent that each tab will show.  This is not sufficient for switching
 * between pages.  So instead we make the content part of the tab host
 * 0dp high (it is not shown) and the TabsAdapter supplies its own dummy
 * view to show as the tab content.  It listens to changes in tabs, and takes
 * care of switch to the correct paged in the ViewPager whenever the selected
 * tab changes.
 */
public static class TabsAdapter extends FragmentPagerAdapter
        implements ActionBar.TabListener, ViewPager.OnPageChangeListener {
    private final Context mContext;
    private final ActionBar mActionBar;
    private final ViewPager mViewPager;
    private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();

    static final class TabInfo {
        private final Class<?> clss;
        private final Bundle args;

        TabInfo(Class<?> _class, Bundle _args) {
            clss = _class;
            args = _args;
        }
    }

    public TabsAdapter(Activity activity, ViewPager pager) {
        super(activity.getFragmentManager());
        mContext = activity;
        mActionBar = activity.getActionBar();
        mViewPager = pager;
        mViewPager.setAdapter(this);
        mViewPager.setOnPageChangeListener(this);
    }

    public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {
        TabInfo info = new TabInfo(clss, args);
        tab.setTag(info);
        tab.setTabListener(this);
        mTabs.add(info);
        mActionBar.addTab(tab);
        notifyDataSetChanged();
    }

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

    @Override
    public Fragment getItem(int position) {
        TabInfo info = mTabs.get(position);
        return Fragment.instantiate(mContext, info.clss.getName(), info.args);
    }

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

    @Override
    public void onPageSelected(int position) {
        mActionBar.setSelectedNavigationItem(position);
    }

    @Override
    public void onPageScrollStateChanged(int state) {
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        Object tag = tab.getTag();
        for (int i=0; i<mTabs.size(); i++) {
            if (mTabs.get(i) == tag) {
                mViewPager.setCurrentItem(i);
            }
        }
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    }
}

}

Answer 1

您可以将数据从Activity传输到Fragment，如下所示：

FragmentA fragmentA = new FragmentA();
Bundle bundle = new Bundle();
bundle.putXXX("YourDataKey", YourDataValue);
fragmentA.setArguments(bundle);
getFragmentManager().beginTransaction().add(fragmentA);

在我的观点中，扩展FragmentActivity的原因是它可以轻松管理Fragment。使用Fragment的优点并不那么简单。请阅读谷歌Android doc： http://developer.android.com/guide/components/fragments.html

Answer 2

当我们想要在Android＆lt;上运行的设备上使用FragmentActivity时，我们会从Fragments延伸3.0。要将Fragments用于Android 2.3.3或类似内容，您需要FragmentActivity中的Android support library。您也可以通过以下方式访问传递给片段的包： -

private void LoadBundle()
{
    Bundle b = getArguments();
        if (b != null) {
        int value=b.getInt("yourkey")
}
}

在片段中的任何位置调用LoadBundle（）方法以加载传递到片段中的数据。

字符串从Activity转移到Fragment

2 个答案: