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我正在尝试使用 2 个选项卡实现一个基本活动，每个选项卡都包含一个列表。按照指南，我编写了以下代码：

MainActivity.java

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Notice that setContentView() is not used, because we use the root
        // android.R.id.content as the container for each fragment

        // setup action bar for tabs
        ActionBar actionBar = getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        actionBar.setDisplayShowTitleEnabled(true);

        ActionBar.Tab tab = actionBar.newTab()
                .setText(R.string.tab_last_transactions)
                .setTabListener(new TabListener<List1Fragment>(
                        this, "list1_fragment", List1Fragment.class));
        actionBar.addTab(tab);

        tab = actionBar.newTab()
                .setText(R.string.tab_accounts_balance)
                .setTabListener(new TabListener<List2Fragment>(
                        this, "list2_fragment", List2Fragment.class));
        actionBar.addTab(tab);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        new MenuInflater(this).inflate(R.menu.home_menu, menu);
        return (super.onCreateOptionsMenu(menu));
    }

}

List1Fragment.java

public class List1Fragment extends ListFragment {

    private static final String[] items = { "Android", "Bluetooth", "Chrome",
            "Docs", "Email", "Facebook", "Google", "Hungary", "Iphone",
            "Korea", "Machintosh", "Nokia", "Orkut", "Picasa", "Singapore",
            "Talk", "Windows", "Youtube" };
    private ArrayList<String> words = null;
    ArrayAdapter<String> adapter = null;

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);


        // Populate list with our static array of titles.
        words = new ArrayList<String>();

        for (String s : items) {
            words.add(s);
        }
        adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, words);
        setListAdapter(adapter);

    }
}

list1_fragment.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

    <ListView android:id="@id/android:list"
              android:layout_width="match_parent"
              android:layout_height="0dp"
              android:background="#00FF00"
              android:layout_weight="1"
              android:drawSelectorOnTop="false"/>

</LinearLayout>

MainActivity 从 LoginActivity 实例化，如下所示：

LoginActivity.java 的一部分

        Intent mainIntent = new Intent(LoginActivity.this, MainActivity.class);
        startActivity(mainIntent);
        finish();

LoginActivity 看起来不错。第一次启动MainActivity，没问题，按预期得到列表：

现在我想查看我的应用程序生命周期，所以我将其更改为横向以杀死它并重新创建它，它会在顶部创建一个额外的列表（如果我切换回纵向，还会再创建一个额外的列表）。活动的（滚动的）似乎是第一个创建的。其他的看起来修复了。

类似的结果发布在另一个主题： 双重名单

如果我检查 (savedInstanceState == null) 并仅在 null 时设置 ListAdapter，它似乎具有所需的行为（只有一个列表），但列表顶部有一个“正在加载...”。添加 setListShown(true) 会抛出异常并退出程序：

修改 List1_Fragment：

if (savedInstanceState==null)
{
    // Populate list with our static array of titles.
    words = new ArrayList<String>();

    for (String s : items) {
        words.add(s);
    }
    adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, words);
    setListAdapter(adapter);

}        
else {
    setListShown(true);
}

我究竟做错了什么？如何避免重新创建列表？

（防止它在改变方向时重新生成不是一个选项，我会在应用程序完成后执行此操作，但想在开发过程中使用此功能测试生命周期，以模拟终止/重新启动）

编辑： 使用 setListShownNoAnimation 而不是 setListShown 工作...

编辑2：

TabListener.java

public class TabListener<T extends Fragment> implements ActionBar.TabListener {
    private Fragment mFragment;
    private final Activity mActivity;
    private final String mTag;
    private final Class<T> mClass;

    /** Constructor used each time a new tab is created.
     * @param activity  The host Activity, used to instantiate the fragment
     * @param tag  The identifier tag for the fragment
     * @param clz  The fragment's Class, used to instantiate the fragment
     */
    public TabListener(Activity activity, String tag, Class<T> clz) {
        mActivity = activity;
        mTag = tag;
        mClass = clz;
    }

    /* The following are each of the ActionBar.TabListener callbacks */

    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
        // Check if the fragment is already initialized
        if (mFragment == null) {
            // If not, instantiate and add it to the activity
            mFragment = Fragment.instantiate(mActivity, mClass.getName());
            ft.add(android.R.id.content, mFragment, mTag);
        } else {
            // If it exists, simply attach it in order to show it
            ft.attach(mFragment);
        }
    }

    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
        if (mFragment != null) {
            // Detach the fragment, because another one is being attached
            ft.detach(mFragment);
        }
    }

    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {
        // User selected the already selected tab. Usually do nothing.
    }
}
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