在TabLayout（材料设计）Android中动态添加和删除选项卡

Question

我有一个TabLayout，里面有ViewPager。我需要动态添加和删除tab在tablayout（材料设计）。我可以动态地添加选项卡，但是在删除选项卡时，选项卡被正确删除。但是viewpager的最后一个项目被删除了。所以选项卡没有显示特定的片段。FYI我已经使用了FragmentPagerAdapter。

我按照这个教程实现了这个功能。

https://androidbelieve.com/navigation-drawer-with-swipe-tabs-using-design-support-library

public class TabFragment extends Fragment {

    public static TabLayout tabLayout;
    public static ViewPager viewPager;
    public static int int_items = 2;
    private MyNewsFragment mMyNewsFragment;
    private ArrayList<TabFragmentModelClass> mFragmentArrayList;
    private TabLayoutAdapter mTabLayoutAdapter;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        mMyNewsFragment = new MyNewsFragment();
        /**
         *Inflate tab_layout and setup Views.i;;a
         */
        View x = inflater.inflate(R.layout.tab_layout, null);
        tabLayout = (TabLayout) x.findViewById(R.id.tabs);
        tabLayout.setTabMode(TabLayout.MODE_SCROLLABLE);  // scorllable tab
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);  // tab name fill parent
        viewPager = (ViewPager) x.findViewById(R.id.viewpager);
        mFragmentArrayList = new ArrayList<>();
        mFragmentArrayList.add(new TabFragmentModelClass(new MyNewsSelectionFragment(), "", ""));
        mFragmentArrayList.add(new TabFragmentModelClass(mMyNewsFragment, "", getResources().getString(R.string.mynews)));
        mFragmentArrayList.add(new TabFragmentModelClass(new BreakingNewsFragment(), "", getResources().getString(R.string.breakingnews)));

        // Selected news from shared preference
        ArrayList<MyNewsSharedPreferenceModelClass> tempSharedPreferenceModelClass = new MyNewsSharedPreferenceClass().loadFavorites(getActivity());
        for (int i = 0; i < tempSharedPreferenceModelClass.size(); i++) {
            mFragmentArrayList.add(new TabFragmentModelClass(new CategoreyNewsFragment(tempSharedPreferenceModelClass.get(i).getmCatID()), tempSharedPreferenceModelClass.get(i).getmCatID(),
                    tempSharedPreferenceModelClass.get(i).getmCatName()));
        }


 }


        /**
         *Set an Apater for the View Pager
         */
        mTabLayoutAdapter = new TabLayoutAdapter(getChildFragmentManager(), mFragmentArrayList);
        viewPager.setAdapter(mTabLayoutAdapter);
        viewPager.setOffscreenPageLimit(mFragmentArrayList.size());
        tabLayout.setupWithViewPager(viewPager);


        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            }

            @Override
            public void onPageSelected(int position) {
                tabLayout.getTabAt(position);
            }

            @Override
            public void onPageScrollStateChanged(int state) {
                if (state == 1) {
                    updateMyNewsFragment();
                }
            }
        });

        /**
         * Now , this is a workaround ,
         * The setupWithViewPager dose't works without the runnable .
         * Maybe a Support Library Bug .
         */

        tabLayout.post(new Runnable() {
            @Override
            public void run() {

                tabLayout.getTabAt(0).setIcon(R.mipmap.mynewselection);

                tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
                    @Override
                    public void onTabSelected(TabLayout.Tab tab) {
                        viewPager.setCurrentItem(tab.getPosition());
                        switch (tab.getPosition()) {
                            case 1:

                                System.out.println("000000000000000000000 ");
                                updateMyNewsFragment();
                                break;
                        }
                    }

                    @Override
                    public void onTabUnselected(TabLayout.Tab tab) {
                    }


                    @Override
                    public void onTabReselected(TabLayout.Tab tab) {
                    }
                });

            }
        });
        return x;
    }

    /**
     * update the mynews selection
     * this method trigger from the MainNewsActivity
     */
    public void updateMyNewsFragment() {
        if (ApplicationController.getInstance().getBoolPref(CommonVariableInterFace.isNewsSelected)) {
            mMyNewsFragment.sendMyNewsRequest();
            ApplicationController.getInstance().setBoolPref(CommonVariableInterFace.isNewsSelected, false);
        }
    }

    /**
     * update the tab values
     * this method trigger from the MainNewsActivity
     * if value is zero need to add in tab
     * if value is one need to remove in tab
     */
    public void updateTabvalue(String catId, String catName, int value) {

            if (value == 0) { // add the value in tab

                mFragmentArrayList.add(new TabFragmentModelClass(new CategoreyNewsFragment(catId), catId,
                        catName));
            }  else {      // Removing the tab
                for (int i = 0; i < mFragmentArrayList.size(); i++) {
                    if (mFragmentArrayList.get(i).getmCatID().equalsIgnoreCase(catId)) {

                        Log.i("-----same id ", catId);
                        mFragmentArrayList.remove(i);
                        mTabLayoutAdapter = new TabLayoutAdapter(getChildFragmentManager(), mFragmentArrayList);
                        viewPager.setAdapter(mTabLayoutAdapter);
                    }
                }
            }

            mTabLayoutAdapter.notifyDataSetChanged();
            viewPager.setOffscreenPageLimit(mFragmentArrayList.size());
            tabLayout.getTabAt(0).setIcon(R.mipmap.mynewselection);
             tabLayout.setupWithViewPager(viewPager);


            tabLayout.post(new Runnable() {
                @Override
                public void run() {

                    tabLayout.getTabAt(0).setIcon(R.mipmap.mynewselection);

                    tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
                        @Override
                        public void onTabSelected(TabLayout.Tab tab) {
                            viewPager.setCurrentItem(tab.getPosition());
                            switch (tab.getPosition()) {
                                case 1:
                                    updateMyNewsFragment();
                                    break;
                            }
                        }

                        @Override
                        public void onTabUnselected(TabLayout.Tab tab) {
                        }


                        @Override
                        public void onTabReselected(TabLayout.Tab tab) {
                        }
                    });

                }
            });
    }

    public void openSpecificTab() {

//        tabLayout.settab
//        tabLayout.se
    }
}

适配器代码：

public class TabLayoutAdapter extends FragmentPagerAdapter {

    private long baseId = 0;
    ArrayList<TabFragmentModelClass> fragmentAdapterArrayList;

    public TabLayoutAdapter(FragmentManager fm, ArrayList<TabFragmentModelClass> fragmentArrayList) {
        super(fm);
        fragmentAdapterArrayList = fragmentArrayList;
    }

    @Override
    public Fragment getItem(int position) {

        if (position == 0)
            return fragmentAdapterArrayList.get(position).getmFragment();
        if (position == 1)
            return fragmentAdapterArrayList.get(position).getmFragment();
        if (position == 2)
            return fragmentAdapterArrayList.get(position).getmFragment();

        return new CategoreyNewsFragment().newInstance(fragmentAdapterArrayList.get(position).getmCatID());
    }

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


    //this is called when notifyDataSetChanged() is called
    @Override
    public int getItemPosition(Object object) {
        // refresh all fragments when data set changed
        return TabLayoutAdapter.POSITION_NONE;
    }


    @Override
    public long getItemId(int position) {
        // give an ID different from position when position has been changed
        return baseId + position;
    }

    /**
     * Notify that the position of a fragment has been changed.
     * Create a new ID for each position to force recreation of the fragment
     *
     * @param n number of items which have been changed
     */
    public void notifyChangeInPosition(int n) {
        // shift the ID returned by getItemId outside the range of all previous fragments
        baseId += getCount() + n;
    }

    /**
     * //     * This method returns the title of the tab according to the position.
     * //
     */

    @Override
    public CharSequence getPageTitle(int position) {
        return fragmentAdapterArrayList.get(position).getmCatName();
    }
}

- Ruban

Answer 1

从 TabLayout 中删除选项卡

...
public void removeTab(int position) {
    if (mTabLayout.getTabCount() >= 1 && position<mTabLayout.getTabCount()) {
          mTabLayout.removeTabAt(position);
          mPagerAdapter.removeTabPage(position);
    }
}
...

添加一个removeTabPage方法到你的PagerAdapter中。

...
public void removeTabPage(int position) {
    if (!tabItems.isEmpty() && position<tabItems.size()) {
          tabItems.remove(position);
          notifyDataSetChanged();
    }
}
...

添加一个选项卡

...
private void addTab(String title) {
        mTabLayout.addTab(mTabLayout.newTab().setText(title));
        mPagerAdapter.addTabPage(title);
}
...

在您的PagerAdapter中添加一个addTabPage方法。

...
public void addTabPage(String title) {
      tabItems.add(title);
      notifyDataSetChanged();
}
...

查看完整示例的示例代码：...samples/SupportDesignDemos/src/com/example/android/support/design/widget/TabLayoutUsage.java

- TouchBoarder

---

我尝试了上述方法，但它对我没有用。在使用具有5个片段的viewpager上调用removeTab(2)后，我得到了以下错误： java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getLeft()' on a null object reference @Ruban - Zvi

@Zvi，这个错误看起来像是你正在尝试在一个不存在的视图上调用View.getLeft()，试着找出原因吧？难道removeTab(2)的调用移除了对这个视图的引用吗？ - TouchBoarder

我解决了这个问题。我是在onTabSelected()中调用removeTab()。一旦我将它移动到活动的主要代码中，问题就消失了。谢谢。 - Zvi

进一步调查发现，与已删除标签相关联的片段，其onCreateView、onViewStateRestored和onResume方法被调用，尽管它不再在适配器列表中。此外，在已删除片段之前，下一个片段（其选项卡现在为tab(2)）的这些方法也被调用。 - Zvi

使用FragmentStatePagerAdapter而不是FragmentPagerAdapter解决了问题。 - Zvi

Answer 2

使用新的支持库（我正在使用23.2.1版本），您只需要添加到Viewpager而不是TabLayout（否则会导致双重标签和其他奇怪的行为）。因此，要更新TouchBoarder的答案：

在您的PagerAdapter中添加removeTabPage方法。

public void removeTabPage(int position) {
    if (!tabItems.isEmpty() && position<tabItems.size()) {
          tabItems.remove(position);
          notifyDataSetChanged();
    }
}

在你的PagerAdapter中添加一个addTabPage方法。

public void addTabPage(String title) {
      tabItems.add(title);
      notifyDataSetChanged();
}

- MidasLefko

---

如果我没有页面适配器而只有选项卡布局怎么办？ - Zulqurnain Jutt

@ZulqurnainJutt：我认为你可以这样做，TabLayout.Tab tab = tabLayout.newTab().setText("General"); tabLayout.addTab(tab); - Monster Brain

Answer 3

除了现有的答案外，要从tabLayout中删除所有选项卡。

tabLayout.removeAllTabs();

- Shahbaz Hashmi

Answer 4

你可以像这样添加动态选项卡：

 public void addTabs(){
    for(YourClassModel tabName: tabsName){
        Log.i("ActivityClass","tabName"+tabName);
        tabLayout.addTab(tabLayout.newTab().setText(tabName.getName()));

    }

- Hanisha Sachdeva

Answer 5

从TabLayout中移除标签

TabActivity和ViewPager代码：

`public class ScrollableTabsActivity extends AppCompatActivity {

int NumberOfTab = 5;
private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
ViewPagerAdapter adapter ;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_scrollable_tabs);

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    adapter = new ViewPagerAdapter(getSupportFragmentManager());
    viewPager = (ViewPager) findViewById(R.id.viewpager);
    setupViewPager(viewPager);

    tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(viewPager);

    int length = tabLayout.getTabCount();

    for (int i = 0; i < length; i++) {
        tabLayout.getTabAt(i).setCustomView(getTabView(i));
    }

}

public View getTabView(final int position) {
    View view = LayoutInflater.from(this).inflate(R.layout.close_tablayout, null);
    TextView title = (TextView) view.findViewById(R.id.title);
    ImageView icon = (ImageView) view.findViewById(R.id.close);
    title.setText(adapter.getPageTitle(position));
    icon.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            NumberOfTab = NumberOfTab - 1;
            setupViewPager(viewPager);
            tabLayout.setupWithViewPager(viewPager);
            if (tabLayout.getTabCount()==3)
                tabLayout.setTabMode(TabLayout.MODE_FIXED);

            int length = tabLayout.getTabCount();
            for (int i = 0; i < length; i++) {
                tabLayout.getTabAt(i).setCustomView(getTabView(i));
            }


        }
    });

    return view;
}

private void setupViewPager(ViewPager viewPager) {
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
    viewPager.setAdapter(adapter);
}

class ViewPagerAdapter extends FragmentPagerAdapter {

    public ViewPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        final Fragment result;
        switch (position) {
            case 0:
                // First Fragment of First Tab
                result = new OneFragment();
                break;
            case 1:
                // First Fragment of Second Tab
                result = new TwoFragment();
                break;
            case 2:
                // First Fragment of Second Tab
                result = new ThreeFragment();
                break;
            case 3:
                // First Fragment of Second Tab
                result = new FourFragment();
                break;

            case 4:
                // First Fragment of Second Tab
                result = new FiveFragment();
                break;

            default:
                result = null;
                break;
        }

        // Log.d("RESULT",result.getTag());
        return result;
    }

    @Override
    public int getCount() {
        return NumberOfTab;
    }

    @Override
    public CharSequence getPageTitle(final int position) {
        switch (position) {
            case 0:
                return "One";
            case 1:
                return "Two";
            case 2:
                return "Three";
            case 3:
                return "Four";
            case 4:
                return "Five";
            default:
                return null;
        }
    }

}

请查看以下链接： https://stackoverflow.com/a/58480151/9223264

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