Question

我正在创建一个使用ActionBarSherlock的应用。该应用程序由三个选项卡组成，在每个选项卡中，根据用户输入连续显示多个屏幕。我可以在选项卡之间切换片段，但在选项卡中切换片段会产生问题。我试过这样的话：

在主要课程中：

SingleStationFragment singleStationFragment = new SingleStationFragment(); FragmentTransaction transaction = getSupportFragmentManager().beginTransaction(); transaction.replace(android.R.id.content, singleStationFragment); transaction.addToBackStack(null); transaction.commit();

此替换第二个片段的第一个片段，但是当我更改制表符时，第二个片段仍然可见，在旧制表符内容的顶部显示新选项卡的内容。我想某种方式我需要在onTabUnselected中分离第二个片段，但我不知道如何获得对这个片段的引用。

任何人都可以帮我吗？

为清楚起见，一些重要的课程：

我的主要课程：

public class TreinVerkeer extends SherlockFragmentActivity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setupTabs(savedInstanceState); } @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getSupportMenuInflater(); inflater.inflate(R.menu.menu, menu); return true; } private void setupTabs(Bundle savedInstanceState) { ActionBar actionBar = getSupportActionBar(); actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); Tab tab = actionBar.newTab().setText("STATIONS").setTabListener(new TabListener<StationsFragment>(this, "stations", StationsFragment.class)); actionBar.addTab(tab); tab = actionBar.newTab().setText("ROUTE").setTabListener(new TabListener<RouteFragment>(this, "route", RouteFragment.class)); actionBar.addTab(tab); tab = actionBar.newTab().setText("DELAYS").setTabListener(new TabListener<DelaysFragment>(this, "delays", DelaysFragment.class)); actionBar.addTab(tab); if (savedInstanceState != null) { actionBar.setSelectedNavigationItem(savedInstanceState.getInt("tab", 0)); } } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putInt("tab", getSupportActionBar().getSelectedNavigationIndex()); } }

TabListener（来自"Adding Navigations Tabs" on the Android developer site稍作修改）：

public class TabListener<T extends SherlockFragment> implements com.actionbarsherlock.app.ActionBar.TabListener { private SherlockFragment 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(Tab tab, FragmentTransaction ft) { SherlockFragment preInitializedFragment = (SherlockFragment) mActivity.getSupportFragmentManager().findFragmentByTag(mTag); // Check if the fragment is already initialized if (mFragment == null && preInitializedFragment == null) { // If not, instantiate and add it to the activity mFragment = (SherlockFragment) SherlockFragment.instantiate(mActivity, mClass.getName()); ft.add(android.R.id.content, mFragment, mTag); } else if (mFragment != null) { // If it exists, simply attach it in order to show it ft.attach(mFragment); } else if (preInitializedFragment != null) { ft.attach(preInitializedFragment); mFragment = preInitializedFragment; } } public void onTabUnselected(Tab tab, FragmentTransaction ft) { if (mFragment != null) { // Detach the fragment, because another one is being attached ft.detach(mFragment); } } public void onTabReselected(Tab tab, FragmentTransaction ft) { // User selected the already selected tab. Usually do nothing. } }

而StationsFragment（RouteFragment和DelaysFragment相同，只有不同的文字）

public class StationsFragment extends SherlockFragment { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(R.layout.stationsfragment, container, false); } }

Answer 1

所发生的事情是，在TabListener中，在onTabUnselected方法中，Fragment没有分离，导致它仍然显示而新的Fragment是所示。

原因是，分离的Fragment是第一个片段，而不是我的第二个片段。我做了一些改变。

在Activity：

中

SingleStationFragment singleStationFragment = new SingleStationFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(android.R.id.content, singleStationFragment, "STATIONS");
transaction.addToBackStack(null);
transaction.commit();

我在"STATIONS"方法中添加了replace()标记，该标记与第一个片段的标记相同。
TabListener现在如下：

public class TabListener<T extends SherlockFragment> implements com.actionbarsherlock.app.ActionBar.TabListener {
    private final SherlockFragmentActivity mActivity;
    private final String mTag;
    private final Class<T> mClass;

    private SherlockFragment mFragment;

    public TabListener(SherlockFragmentActivity activity, String tag, Class<T> clz) {
        mActivity = activity;
        mTag = tag;
        mClass = clz;
    }

    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        SherlockFragment preInitializedFragment = (SherlockFragment) mActivity.getSupportFragmentManager().findFragmentByTag(mTag);
        if (preInitializedFragment == null) {
            mFragment = (SherlockFragment) SherlockFragment.instantiate(mActivity, mClass.getName());
            ft.add(R.id.treinverkeer_fragmentcontent, mFragment, mTag);
        } else {
            ft.attach(preInitializedFragment);
        }
    }

    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        SherlockFragment preInitializedFragment = (SherlockFragment) mActivity.getSupportFragmentManager().findFragmentByTag(mTag);

        if (preInitializedFragment != null) {
            ft.detach(preInitializedFragment);
        } else if (mFragment != null) {
            ft.detach(mFragment);
        }
    }

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

在onTabUnselected方法中，我现在首先检索正确的Fragment，然后将其分离。

希望这有助于某人！

在标签内切换片段

1 个答案: