如何删除带有actionbar,viewpager和多个片段的选项卡？

Question

我正在使用我在这里找到的代码.

public class ActionBarTabs extends SherlockFragmentActivity {
CustomViewPager mViewPager;
TabsAdapter mTabsAdapter;
TextView tabCenter;
TextView tabText;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);

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

    setContentView(mViewPager);
    ActionBar bar = getSupportActionBar();
    bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
    bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);

    mTabsAdapter = new TabsAdapter(this, mViewPager);

    mTabsAdapter.addTab(bar.newTab().setText("Home"),
            ToolKitFragment.class, null);
    mTabsAdapter.addTab(bar.newTab().setText("FujiSan"),
            FujiFragment.class, null);
}

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(SherlockFragmentActivity activity, ViewPager pager) {
        super(activity.getSupportFragmentManager());
        mContext = activity;
        mActionBar = activity.getSupportActionBar();
        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) {
    }
}
}

我正在尝试修改它,以便我可以动态删除标签.我试过简单地创建这个函数:

    public void removeTab(ActionBar.Tab tab) {
        mTabs.remove(tab);
        mActionBar.removeTab(tab);
        notifyDataSetChanged();
    }

但我总是得到一个indexoutofboundsexception.有谁知道这样做的好方法？

编辑

通过将我的方法更改为:

    public void removeTab(ActionBar.Tab tab) {
        mTabs.remove(tab.getTag());
        mActionBar.removeTab(tab);
        notifyDataSetChanged();
    }

我能够成功删除标签.但是,当我删除不是最右边的选项卡时,与选项卡关联的视图(或片段？)不会消失.相反,它似乎与下一个最高标签相关联.例如,如果我删除了选项卡0,则选项卡0的视图将移至选项卡1.如果我删除具有最高ID的选项卡,则选项卡和视图将正确消失,但在添加新选项卡时则返回COME BACK.

就好像有一个与选项卡关联的片段列表,删除选项卡不会删除片段.有谁知道是什么导致了这个？

EDIT2

我试图删除片段:

            Fragment fragmentToRemove = getItem(tab.getPosition());
            destroyItem(mViewPager, tab.getPosition(), fragmentToRemove);

并且

        Fragment fragmentToRemove = getItem(tab.getPosition());
        FragmentTransaction fragmentTransaction = mActivity
                .getSupportFragmentManager().beginTransaction();
        fragmentTransaction.remove(fragmentToRemove);
        fragmentTransaction.commit();

但迄今为止都没有奏效.

Answer 1

得到它了!

public void removeTab(ActionBar.Tab tab) {
    mTabs.remove(tab.getTag());
    mActionBar.removeTab(tab);
    notifyDataSetChanged();
}

并覆盖destroyItem

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        // TODO Auto-generated method stub
        super.destroyItem(container, position, object);
        FragmentManager manager = ((Fragment) object).getFragmentManager();
        FragmentTransaction trans = manager.beginTransaction();
        trans.remove((Fragment) object);
        trans.commit();
    }

完美的工作!

Answer 2

我今天才发现支持插入或删除标签的真正技巧是覆盖FragmentPagerAdapter.getItemPosition():

@Override
public int getItemPosition(Object object) {
    Fragment fragment = (Fragment) object;
    for (int i = 0; i < tabInfos.size(); i++) {
        if (tabInfos.get(i).clss == fragment.getClass()) {
            return i;
        }
    }
    // The tab must have been removed
    return POSITION_NONE;
}

getItemPosition()将ViewPager在您调用notifyDataSetChanged()之后调用(在添加/删除选项卡之后).在ViewPager试图重新同步缓存与此适配器.它要求getItemPosition()它拥有的每个"对象"(片段),我们告诉它片段来自哪个位置.如果没有匹配,那是因为我们删除了该选项卡,所以返回POSITION_NONE.

我还发现,FragmentPagerAdapter.getItemId()如果插入或删除标签,重写是很重要的,因为片段将左右移动位置.此方法由项调用FragmentPagerAdapter.instantiateItem()并附加到项的名称(String).它使用此名称查找具有匹配名称(如果有)的预先存在的片段,否则将实例化新的片段.这是一些代码:

@Override
public long getItemId(int position) {
    TabInfo info = tabInfos.get(position);
    // The default hashCode() implementation is based on memory address, which will be unique
    int hash = info.clss.hashCode();
    return hash;
}