getSupportFragmentManager getFragment 不带标签或 id

我正在开发 Android 3.1 平板电脑应用程序。

我在一项活动中使用 ViewPager 和片段。我的问题是我不知道如何为片段设置 ID 或标签。

Activity

public class FillEReportFragmentActivity extends FragmentActivity
{
    ...

    /**
     * View Pager to manage form parts.
     */
    private ViewPager mViewPager;
    /**
     * Page Adapter to handle fragments.
     */
    private FillEReportFragmentPagerAdapter mPagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstance)
    {
        Log.v("FillEReportFragmentActivity", "onCreate");

        super.onCreate(savedInstance);
        setContentView(R.layout.fill_ereport_paged);

        // Recoge los argumentos que le llegan de la actividad padre.
        Bundle extras = getIntent().getExtras();
        if (extras != null)
        {
            qapId = extras.getLong(BundleKeys.qapIdKey);
            orderId = extras.getLong(BundleKeys.orderIdKey);
            eReportId = extras.getLong(BundleKeys.eReportIdKey);
        }

        // Cargamos el E-Report o creamos uno nuevo. Además se recuperan los
        // artículos de la orden actual.
        LoadEReportAsyncTask task = new LoadEReportAsyncTask(this);
        task.execute(Long.toString(this.qapId));

        // Establezco los fragmentos (o partes del form) que se mostrarán en el
        // View Pager.
        mViewPager = (ViewPager)findViewById(R.id.pager);
        mPagerAdapter = new FillEReportFragmentPagerAdapter(getSupportFragmentManager());
        mViewPager.setAdapter(mPagerAdapter);

        // Muestro en la parte inferior unos círculos para indicar donde me
        // encuentro dentro del E-Report.
        CirclePageIndicator mIndicator = (CirclePageIndicator)findViewById(R.id.indicator);
        mIndicator.setViewPager(mViewPager);

        // Creo unos tabs para poder navegar más facilmente a través de las
        // partes del E-Report.
        TabPageIndicator titleIndicator = (TabPageIndicator)findViewById(R.id.tabIndicator);
        titleIndicator.setViewPager(mViewPager);
    }

        ...
}

FragmentPagerAdapter

public class FillEReportFragmentPagerAdapter extends FragmentPagerAdapter
{
    private static final String[] TITLES = new String[] { 
        "Factory", 
        "Items" 
    };

    public FillEReportFragmentPagerAdapter(FragmentManager fm)
    {
        super(fm);
        // TODO Auto-generated constructor stub
    }

    @Override
    public Fragment getItem(int index)
    {
        switch (index)
        {
            case 0:
                return FactoryInfoFragment.newInstance();
            case 1:
                return ItemsFragment.newInstance();

        default:
            return null;
        }
    }

    @Override
    public int getCount()
    {
        return 2; // TODO: Este número hay que cambiarlo porque serán más.
    }

    public String getPageTitle(int position)
    {
        return TITLES[position];
    }
}

资源/值/ids.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item type="id" name="frag_general_info_factory"/>
    <item type="id" name="frag_general_info_items"/>
</resources>

工厂信息片段

public class FactoryInfoFragment extends Fragment
{
    public static FactoryInfoFragment newInstance()
    {
        FactoryInfoFragment frag = new FactoryInfoFragment();

        return frag;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState)
    {
        Log.v("FactoryInfoFragment", "onCreateView");

        View v = inflater.inflate(R.layout.frag_general_info_factory, container, false);
    view.setId(R.id.frag_general_info_factory);

        return v;
    }
}

frag_general_info_factory.xml

<?xml version="1.0" encoding="utf-8"?>
<TableLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_margin="10dp"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:shrinkColumns="*"  
    android:stretchColumns="*">

      <TableRow
        android:weightSum="1"> <!-- 0 -->
    <TextView
        android:id="@+id/txtGenInfo"
        android:layout_span="8"
        android:layout_gravity="center_horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/layout_title_general_information"
        android:textAppearance="?android:attr/textAppearanceLarge" />
      </TableRow>

      ...

</TableLayout>

这里我想获取一个特定的片段

private class LoadEReportAsyncTask extends AsyncTask<String, Void, Boolean>
{
    private Context mContext;
    private ProgressDialog loadingDialog;
    private EReport eReport;
    private QAP qap;

    public LoadEReportAsyncTask(Context context)
    {
        Log.v("LoadEReportAsyncTask", "constructor");
        eReport = null;
        qap = null;

        this.mContext = context;
        loadingDialog = new ProgressDialog(mContext);
        loadingDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        loadingDialog.setMessage(getString(R.string.msg_loading_ereport));
        loadingDialog.setCancelable(false);
        loadingDialog.show();
    }

    @Override
    protected Boolean doInBackground(String... params)
    {
        Log.v("LoadEReportAsyncTask", "doInBackground");
        ...
    }

    protected void onPostExecute(Boolean result)
    {
        Log.v("LoadEReportAsyncTask", "onPostExecute");

        FillEReportFragmentActivity parentActivity = (FillEReportFragmentActivity) mContext;
        if (result)
        {
            FactoryInfoFragment factFragment = (FactoryInfoFragment)getSupportFragmentManager().findFragmentById(R.id.frag_general_info_factory);
            factFragment.fillEReport(eReport, qap);

            Toast.makeText(getApplicationContext(), getString(R.string.msg_ereport_got_correct), Toast.LENGTH_SHORT).show();

            ItemsFragment fragment = (ItemsFragment)getSupportFragmentManager().findFragmentById(R.id.frag_general_info_items);
            fragment.setUpArticles(orderArticles);
        }
        else
        {
            Toast.makeText(getApplicationContext(), getString(R.string.msg_ereport_problem), Toast.LENGTH_LONG).show();
        }

        loadingDialog.dismiss();
    }
}

Here:

(FactoryInfoFragment)getSupportFragmentManager().findFragmentById(R.id.frag_general_info_factory);

I use R.id.frag_general_info_factory获得该片段参考，但我得到了null.

如何设置标签或 IDFactoryInfoFragment?

我没试过，但不知道行不行findFragmentById()在这种情况下将正常工作，因为实际上有多个片段与 ViewPager 容器关联。

如果你看一下源代码FragmentPagerAdapter您可以看到它如何在内部使用标签。那么也许你会覆盖instantiateItem()在您的自定义寻呼机适配器中，复制以下代码FragmentPagerAdapter并调整它以使用标签，您也可以在代码中的其他地方使用这些标签来自己检索片段。

例如，如果您的 PagerAdapter 实现可能专门针对这一问题，那么您可以执行如下简单的操作：

private String getTag(int position) {
    switch (position) {
    case 0:
        return FactoryInfoFragment.class.toString();
    case 1:
        return ItemsFragment.class.toString();
    default:
        return "unknown:" + position;
}