ViewPager中的片段视图在恢复时未恢复

问题描述

我设置了 ActionBar 标签.它由 4 个选项卡组成.一切都很好，直到我离开 TabbedFragment 并返回.

我创建这样的标签:

 @Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);最终 ActionBar actionBar = getActionBar();tabs = Lists.newArrayList();tabs.add(new TabDefinition<>("Tab 1"));tabs.add(new TabDefinition<>("Tab 2"));tabs.add(new TabDefinition<>("Tab 3"));tabs.add(new TabDefinition<>("Tab 4"));for (TabDefinition tab : tabs) {actionBar.addTab(actionBar.newTab().setText(tab.text).setTag(tab.tag).setTabListener(this));}}

并像这样初始化适配器:

@Override公共视图 onCreateView(LayoutInflater inflater，ViewGroup 容器，Bundle savedInstanceState) {返回 inflater.inflate(R.layout.paging_tab_container, container, false);}@覆盖public void onViewCreated(View view, Bundle savedInstanceState) {super.onViewCreated(view,savedInstanceState);viewPager = (ViewPager) view.findViewById(R.id.pager);viewPager.setAdapter(new FragmentStatePagerAdapter(getFragmentManager()) {@覆盖公共片段 getItem(int position) {返回 tabs.get(position).fragment;}@覆盖公共 int getCount() {返回 tabs.size();}});viewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {@覆盖public void onPageSelected(int position) {getActionBar().setSelectedNavigationItem(position);}});viewPager.setCurrentItem(getActionBar().getSelectedNavigationIndex(), true);}

当返回到 TabbedFragment 选择的选项卡和它旁边的 1 时不会有任何内容.只是空观.但是如果我选择当前 + 2 片段内容被加载.然后返回到第一个片段内容被重新加载.
例如，我有 A、B、C、D 选项卡.在离开 TabbedFragment 之前，我选择了选项卡 A.当返回到 TabbedFragment 时，我仍然在选项卡 A，但它是空的.选项卡 B 也是如此.
But when selecting tab C it is created and loaded.返回到选项卡 A，它被重新创建.

这里可能有什么问题?

解决方案

过了一会儿又遇到同样的问题，所以更新这个问题.如果您使用 FragmentStatePagerAdapter，您应该通过 getChildFragmentManager() 而不是 getFragmentManager() 提供 FragmentManager.请参阅问题 55068:ViewPager 在通过 backstack 返回导航时不刷新子片段>

I have ActionBar Tabs setup. It consists of 4 tabs. Everything is fine until I navigate away from TabbedFragment and returning back.

I create tabs like this:

  @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        final ActionBar actionBar = getActionBar();

        tabs = Lists.newArrayList();
        tabs.add(new TabDefinition<>("Tab 1"));
        tabs.add(new TabDefinition<>("Tab 2"));
        tabs.add(new TabDefinition<>("Tab 3"));
        tabs.add(new TabDefinition<>("Tab 4"));


        for (TabDefinition tab : tabs) {
            actionBar.addTab(actionBar.newTab()
                .setText(tab.text)
                .setTag(tab.tag)
                .setTabListener(this));
        }
    }

And initialize adapter like this:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    return inflater.inflate(R.layout.paging_tab_container, container, false);
}

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    viewPager = (ViewPager) view.findViewById(R.id.pager);

    viewPager.setAdapter(new FragmentStatePagerAdapter(getFragmentManager()) {

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

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

    viewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            getActionBar().setSelectedNavigationItem(position);
        }
    });

    viewPager.setCurrentItem(getActionBar().getSelectedNavigationIndex(), true);
}

When returning back to TabbedFragment selected tab and 1 next to it would not have any content. Just empty view. But if I select current + 2 fragment content is loaded. And then returning to that first fragment content is reloaded.
For example I have A, B, C, D tabs. Before leaving TabbedFragment I had selected tab A.When returning to TabbedFragment I still am at tab A, but it's empty. So is tab B.
But when selecting tab C it is created and loaded. Returning to tab A it is recreated.

What could be the problem here?

解决方案

After a while ran into the same problem again, so updating this question.If you're using FragmentStatePagerAdapter you should provide FragmentManager via getChildFragmentManager() instead of getFragmentManager(). See Issue 55068: ViewPager doesn't refresh child fragments when back navigation via backstack

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