从viewpager动态添加和删除片段时崩溃

Question

我正在使用TabLayout和ViewPager（碎片化的webview）来获取选项卡式浏览器。我面临的问题是当我删除任何选项卡时，我的应用程序崩溃，期望选项卡布局中的第一个和最后一个选项卡。

在这种情况下，我们还会从包含Fragment的ViewPager中删除关联的WebView。

之后，我们再次添加多个标签，然后删除应用程序崩溃。

添加功能

private void addViewPagerAndTab(String tag) {
    mTabTags.add(tag);

    MyFragment browserWebviewFragment = new MyFragment();
    Bundle bundle = new Bundle();
    String timestamp = System.currentTimeMillis() + "";
    bundle.putString("timestamp", timestamp);
    browserWebviewFragment.setArguments(bundle);

    adapter.addFrag(browserWebviewFragment, "TAB " + countTabHeading, "TAB " + countTabHeading, timestamp);
    countTabHeading++;

    if (adapter != null) {
        adapter.notifyDataSetChanged();
    }
    tabLayout.setupWithViewPager(viewPager);
    tabLayout.setScrollPosition(((mTabTags.size()) + 1), 0f, true);
    viewPager.setCurrentItem(((mTabTags.size()) + 1));

    setupTabIcons();
    }

删除功能

private void removeTabs() {
    int position = tabLayout.getSelectedTabPosition();

    if (deleteTabPosition > position) {
        mTabTags.remove(deleteTabPosition);
        tabLayout.removeTabAt(deleteTabPosition);
        adapter.removeViewPagerView(deleteTabPosition);
    } else if (deleteTabPosition < position) {
        mTabTags.remove(deleteTabPosition);
        tabLayout.removeTabAt(deleteTabPosition);
        adapter.removeViewPagerView(deleteTabPosition);
        tabLayout.setScrollPosition(position - 1, 0f, true);
        viewPager.setCurrentItem(position - 1);
    } else {
        int tabCount = tabLayout.getTabCount();

        if (tabCount > position + 1) {
            mTabTags.remove(deleteTabPosition);
            tabLayout.removeTabAt(deleteTabPosition);
            adapter.removeViewPagerView(deleteTabPosition);
            tabLayout.setScrollPosition(position, 0f, true);
            viewPager.setCurrentItem(position);
        } else if (tabCount <= position + 1) {
            mTabTags.remove(deleteTabPosition);
            tabLayout.removeTabAt(deleteTabPosition);
            adapter.removeViewPagerView(deleteTabPosition);
            tabLayout.setScrollPosition(position - 1, 0f, true);
            viewPager.setCurrentItem(position - 1);
        }
    }
}

ViewPager适配器

 private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<TabInfo> mFragmentTitleList = new ArrayList<TabInfo>();
private int deleteTabPosition = -1;

 class ViewPagerAdapter extends  FragmentStatePagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

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

    public void addFrag(Fragment fragment, String title, String url, String timestamp) {
        mFragmentList.add(fragment);
        TabInfo infoTab = new TabInfo();
        infoTab.setStrTabName(title);
        infoTab.setStrTabUrl(url);
        infoTab.setTimestamp(timestamp);
        mFragmentTitleList.add(infoTab);
    }


    @Override
    public int getItemPosition(Object object) {
        Fragment fragmentTemp = (Fragment) object;
        if (mFragmentList.contains(fragmentTemp)) {
            return mFragmentList.indexOf((Fragment) object);
        } else {
            return POSITION_NONE;
        }
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position).getStrTabName();
    }

    public View getTabView(final int position) {
        View v = LayoutInflater.from(MainActivity.this).inflate(R.layout.tab_bg, null);
        TextView tv = (TextView) v.findViewById(R.id.tvTab);
        tv.setText(mFragmentTitleList.get(position).getStrTabName());
        final ImageView img = (ImageView) v.findViewById(R.id.ic_tab_close);
        img.setImageResource(R.drawable.ic_tab_close);
        img.setTag(mFragmentTitleList.get(position).getTimestamp());
        img.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String strTag = (String) v.getTag();
                deleteTabPosition = -1;

                if (mFragmentTitleList != null) {
                    for (int i = 0; i < mFragmentTitleList.size(); ++i) {
                        if (mFragmentTitleList.get(i).getTimestamp().equals(strTag)) {
                            deleteTabPosition = i;
                            break;
                        }
                    }
                }
                if (tabLayout.getTabCount() != 1) {
                    removeTabs();
                } else {

                }
            }
        });
        return v;
    }


    /*
    * Remove the View pager page associated with Tab
    * */
    public void removeViewPagerView(int position) {
        mFragmentList.remove(position);
        mFragmentTitleList.remove(position);
        this.notifyDataSetChanged();
    }
}

以下链接上的完整源代码 http://45.33.27.221/CustomTabNoida.zip

java.lang.IllegalStateException: Fragment already active
at android.support.v4.app.Fragment.setInitialSavedState(Fragment.java:574)
at android.support.v4.app.FragmentStatePagerAdapter.instantiateItem(FragmentStatePagerAdapter.java:110)
at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:870)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1054)
at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:552)
at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:514)
at android.support.v4.view.ViewPager.dataSetChanged(ViewPager.java:946)
at android.support.v4.view.ViewPager$PagerObserver.onChanged(ViewPager.java:2910)
at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
at android.support.v4.view.PagerAdapter.notifyDataSetChanged(PagerAdapter.java:276)
at com.sourcefuse.sns.views.Activities.HomeScreenActivity.addViewPagerAndTab(HomeScreenActivity.java:603)
at com.sourcefuse.sns.views.Activities.HomeScreenActivity.onClick(HomeScreenActivity.java:525)
at android.view.View.performClick(View.java:5204)
at android.view.View$PerformClick.run(View.java:21153)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)