android - 显示内容两次的 fragment

Question

我将解释我的应用程序的结构:

Activity --> fragment A(在该 fragment (A) 中我有 3 个 fragment (B、C、D)(viewpager)) --> 在第一个 fragment (B) 中它包含一个 ListView 。该列表中的每个项目都会启动一个 fragment E。

所以我在这里遇到了一个问题。

当我第一次启动我的应用程序时，一切看起来都很好。

但是当 Fragment E 在屏幕上可见时，选项卡变得很奇怪，就像:

是的!他们被复制了。当我点击 ListView 时，我从 Activity 中的回调提交 2 个 fragment 之间的转换:

    transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.content_frame, PF);
    transaction.addToBackStack(null);
    transaction.commit();

当我想回到上一个 fragment 时:

        getFragmentManager().popBackStack();

是否重新创建了之前的 fragment ？我能做些什么来解决它？

更新 --代码: Activity :

public class MainActivity extends FragmentActivity implements
        IslamToolsFragment.OnToolsSelectedListener {
    FragmentTransaction transaction;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (findViewById(R.id.content_frame) != null) {
            if (savedInstanceState != null) {
                return;
            }

            PagerActivity firstFragment = new PagerActivity();

            getSupportFragmentManager().beginTransaction()
                    .add(R.id.content_frame, firstFragment).commit();
        }
    }

    @Override
    public void OnToolSelected(int position) {
        // TODO Auto-generated method stub
        switch (position) {
        case 0:
            PrayerFragment PF = new PrayerFragment();
            transaction = getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.content_frame, PF);
            transaction.addToBackStack(null);
            transaction.commit();
            break;
        case 1:
            QiblaFragment QF = new QiblaFragment();
            transaction = getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.content_frame, QF);
            transaction.addToBackStack(null);
            transaction.commit();
            break;
        }
    }

fragment A(包含 3 个 fragment ):

public class PagerActivity extends Fragment implements ActionBar.TabListener {
    int NUM_PAGES = 5;
    ActionBar actionBar;
    private ViewPager mPager;
    AppSectionsPagerAdapter mAppSectionsPagerAdapter;

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        mPager.setAdapter(null);
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onActivityCreated(savedInstanceState);
        if (savedInstanceState != null) {
            return;
        } else {

            actionBar = this.getActivity().getActionBar();
            actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
            actionBar.setDisplayShowHomeEnabled(false);
            actionBar.setDisplayShowTitleEnabled(false);
            mAppSectionsPagerAdapter = new AppSectionsPagerAdapter(
                    getChildFragmentManager());
            mPager.setAdapter(mAppSectionsPagerAdapter);
            int icons[] = { R.drawable.ic_action_storage,
                    R.drawable.ic_action_overflow, R.drawable.ic_action_person };
            mPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
                @Override
                public void onPageSelected(int position) {

                    actionBar.setSelectedNavigationItem(position);
                }
            });

            for (int i = 0; i < mAppSectionsPagerAdapter.getCount(); i++) {

                actionBar.addTab(actionBar.newTab().setIcon(icons[i])
                        .setTabListener(this));

            }
        }
    }

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        View tabsview = inflater.inflate(R.layout.pager_activity, container,
                false);
        mPager = (ViewPager) tabsview.findViewById(R.id.pager);

        return tabsview;

    }

fragment B:

public class IslamToolsFragment extends Fragment {
    OnToolsSelectedListener mCallback;

    ListView islamtools;
    Fragment PF = new PrayerFragment();

    public interface OnToolsSelectedListener {
        public void OnToolSelected(int position);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View islamtoolsview = inflater.inflate(R.layout.lvislamtools,
                container, false);
        if (savedInstanceState != null) {
            return islamtoolsview;
        }
        islamtools = (ListView) islamtoolsview.findViewById(R.id.lvislamtools);
        String[] title = { "Prayer Times", "Qibla", "Ahadith", "Quran",
                "Hijri Calendar", "99 Names" };
        IslamToolsAdapter ITA = new IslamToolsAdapter(this.getActivity(), title);
        islamtools.setAdapter(ITA);
        islamtools.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                    long arg3) {
                // TODO Auto-generated method stub
                mCallback.OnToolSelected(arg2);
            }

        });
        return islamtoolsview;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mCallback = (OnToolsSelectedListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnHeadlineSelectedListener");
        }

    }

谢谢!它与保存的实例状态有关吗？

Answer 1

你的代码设计有点错误， fragment 实际上是 Activity 的 fragment ，在这种情况下创建一个包含更多 fragment 的 fragment 对我来说没有意义，你应该做的是为 viewpager 创建一个 Activity 和将您的 3 个 fragment 放入该 Activity 中。

我有一个类似的应用程序，这就是我处理选项卡之间导航的方式:

pager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
            actionBar.setSelectedNavigationItem(position);
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }

上面的代码改变了操作栏的选择项，但没有改变 View 分页标签下面的 View ，你需要执行以下操作来做到这一点:

     @Override
     public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    pager.setCurrentItem(tab.getPosition());
}

@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {

}

@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {

}