【问题标题】:Dynamically add and remove tabs in TabLayout(material design) android在TabLayout(材料设计)android中动态添加和删除标签
【发布时间】:2016-03-22 06:17:15
【问题描述】:

我有一个 TabLayout,里面有 ViewPager。我需要在标签布局(材料设计)中动态添加和删除标签。我可以动态添加选项卡,但是在删除选项卡时,选项卡正在正确删除。但是viewpager最后一项被删除了。所以选项卡没有显示特定的片段。仅供参考,我使用了 FragmentPagerAdapter。

我已经按照这个教程来实现这个

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();
    }
}

【问题讨论】:

    标签: android android-viewpager android-design-library android-tablayout


    【解决方案1】:

    TabLayout删除标签

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

    removeTabPage 方法添加到您的PagerAdapter

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

    添加Tab

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

    addTabPage 方法添加到您的PagerAdapter

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

    查看此示例代码以获取完整示例:...samples/SupportDesignDemos/src/com/example/android/support/design/widget/TabLayoutUsage.java

    【讨论】:

    • 谢谢老兄,很有用
    • 我尝试了上述方法,但它对我不起作用。在带有 5 个片段的 viewpager 上调用 removeTab(2) 后,我收到错误 java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getLeft()' on an null object reference @Ruban
    • @Zvi 这个错误看起来像你试图在不存在的视图上调用 View.getLeft() ,试着找出原因?对 removeTab(2) 的调用是否删除了对该视图的引用?
    • 我解决了这个问题。我从 onTabSelected() 中调用 removeTab()。一旦我将其移至活动的主代码,问题就消失了。谢谢
    • 使用 FragmentStatePagerAdapter 而不是 FragmentPagerAdapter 解决的问题
    【解决方案2】:

    使用新的支持库(我使用的是 23.2.1),您应该只添加到 Viewpager 而不是 TabLayout(否则您最终会出现双标签和其他时髦的行为)。所以要更新TouchBoarder's answer

    将 removeTabPage 方法添加到您的 PagerAdapter

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

    向您的 PagerAdapter 添加一个 addTabPage 方法

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

    【讨论】:

    • 如果我没有页面适配器怎么办?并且只有标签布局?
    • @ZulqurnainJutt:我认为你可以这样做 TabLayout.Tab tab = tabLayout.newTab().setText("General"); tabLayout.addTab(tab);
    【解决方案3】:

    除了现有答案之外,从 tabLayout 中删除所有选项卡。

    tabLayout.removeAllTabs();
    

    【讨论】:

      【解决方案4】:

      您可以像这样添加动态标签:

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

      【讨论】:

        【解决方案5】:

        从标签布局中移除标签

        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;
                }
            }
        
        }
        

        }`

        查看此链接: https://stackoverflow.com/a/58480151/9223264

        我是stackoverflow的新手,如果您认为我的回答有用,我会尽力而为,请欣赏

        【讨论】:

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