更换页面后，选项卡内容消失了。

Question

我在包含ViewPager的Fragment中使用Tab（TabHost或TabContent）时遇到了奇怪的问题。

问题是，当我改变页面后，再回到带有tab和viewPager的Fragment时，我的内容或视图会消失。

->

这是我TabFragment的代码：

package com.halo.mobi.fragment;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.HorizontalScrollView;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;
import android.widget.TabHost.TabContentFactory;
import android.widget.TabWidget;
import android.widget.TextView;
import com.halo.mobi.R;

public class GameTabFragment extends Fragment {
    Activity myActivity;

    TabWidget tab;
    TabHost tabHost;
    ViewPager pager;
    HorizontalScrollView hsvTab;

    List<String> headers;

    TabPagerAdapter adapter;
    TabContentFactory fac;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        myActivity = this.getActivity();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);
        View rootView = inflater.inflate(R.layout.game_list_tab_fragment,
                container, false);

        headers = new ArrayList<String>();

        tabHost = (TabHost) rootView.findViewById(R.id.tabHost);
        pager = (ViewPager) rootView.findViewById(R.id.pager);
        hsvTab = (HorizontalScrollView) rootView.findViewById(R.id.hsvTab);
        hsvTab.setHorizontalScrollBarEnabled(false);

        tabHost.setup();
        fac = new TabContentFactory() {

            @Override
            public View createTabContent(String tag) {
                // TODO Auto-generated method stub
                return new View(myActivity);
            }
        };
        tabHost.addTab(tabHost.newTabSpec("cat")
                .setIndicator(getTabIndicator(myActivity, "CATEGORIES"))
                .setContent(fac));
        tabHost.addTab(tabHost.newTabSpec("new")
                .setIndicator(getTabIndicator(myActivity, "NEW RELEASE"))
                .setContent(fac));
        tabHost.addTab(tabHost.newTabSpec("free")
                .setIndicator(getTabIndicator(myActivity, "TOP FREE"))
                .setContent(fac));
        tabHost.addTab(tabHost.newTabSpec("paid")
                .setIndicator(getTabIndicator(myActivity, "TOP PAID"))
                .setContent(fac));
        tabHost.getTabWidget().setBackgroundColor(
                getResources().getColor(R.color.merah));

        tabHost.setOnTabChangedListener(new OnTabChangeListener() {

            @Override
            public void onTabChanged(String tabId) {
                // TODO Auto-generated method stub
                pager.setCurrentItem(tabHost.getCurrentTab());
                hsvTab.smoothScrollTo(
                        tabHost.getTabWidget()
                                .getChildTabViewAt(tabHost.getCurrentTab())
                                .getLeft(), 0);
            }
        });

        adapter = new TabPagerAdapter(this.getFragmentManager());
        pager.setAdapter(adapter);
        pager.setOffscreenPageLimit(5);
        pager.setOnPageChangeListener(new OnPageChangeListener() {

            @Override
            public void onPageSelected(int arg0) {
                // TODO Auto-generated method stub
                tabHost.setCurrentTab(arg0);
            }
            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {
                // TODO Auto-generated method stub
            }

            @Override
            public void onPageScrollStateChanged(int arg0) {
                // TODO Auto-generated method stub
            }
        });

        return rootView;
    }
    private View getTabIndicator(Context context, String title) {
        View view = LayoutInflater.from(context).inflate(
                R.layout.gametablayout, null);
        TextView tv = (TextView) view.findViewById(R.id.txtTitle);
        tv.setText(title);
        tv.setSingleLine();
        view.setPadding(2, 0, 2, 0);
        return view;
    }
    private class TabPagerAdapter extends FragmentPagerAdapter {
        GameCategoryFragment cat;
        GameNewReleaseFragment newrelease;
        GameTopFreeFragment topfree;
        GameTopPaidFragment toppaid;

        public TabPagerAdapter(FragmentManager fm) {
            super(fm);

            cat = new GameCategoryFragment();
            newrelease = new GameNewReleaseFragment();
            topfree = new GameTopFreeFragment();
            toppaid = new GameTopPaidFragment();
            // TODO Auto-generated constructor stub
        }

        @Override
        public Fragment getItem(int pos) {
            // TODO Auto-generated method stub
            if (pos == 0)
                return cat;
            if (pos == 1)
                return newrelease;
            if (pos == 2)
                return topfree;
            if (pos == 3)
                return toppaid;
            return cat;

        }
        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return 4;
        }
    }
}

游戏列表选项卡片段.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="top|left"
        android:orientation="vertical" >

        <TabHost
            android:id="@+id/tabHost"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" >

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical" >

                <HorizontalScrollView
                    android:id="@+id/hsvTab"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@color/merah" >

                    <TabWidget
                        android:id="@android:id/tabs"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content" >
                    </TabWidget>
                </HorizontalScrollView>

                <FrameLayout
                    android:id="@android:id/tabcontent"
                    android:layout_width="match_parent"
                    android:layout_height="0px"
                    android:orientation="vertical" >
                </FrameLayout>

                <android.support.v4.view.ViewPager
                    android:id="@+id/pager"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />
            </LinearLayout>
        </TabHost>
    </LinearLayout>
</FrameLayout>

这是MainActivity.java文件的代码：

package com.halo.mobi.activity;

import android.os.Bundle;
import android.support.v4.app.FragmentManager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBar.LayoutParams;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;

import com.halo.mobi.R;
import com.halo.mobi.fragment.GameDetailFragment;
import com.halo.mobi.fragment.GameTabFragment;
import com.halo.mobi.fragment.HomeFragment;
import com.halo.mobi.fragment.NavigationDrawerFragment;

public class MainActivity extends ActionBarActivity implements
        NavigationDrawerFragment.NavigationDrawerCallbacks {

    /**
     * Fragment managing the behaviors, interactions and presentation of the
     * navigation drawer.
     */
    private NavigationDrawerFragment mNavigationDrawerFragment;

    private DrawerLayout drawerLayout;
    /**
     * Used to store the last screen title. For use in
     * {@link #restoreActionBar()}.
     */
    private int pos;
    FragmentManager fragmentManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        restoreActionBar();

        mNavigationDrawerFragment = (NavigationDrawerFragment) getSupportFragmentManager()
                .findFragmentById(R.id.navigation_drawer);
        drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);

        // Set up the drawer.
        mNavigationDrawerFragment.setUp(R.id.navigation_drawer, drawerLayout);
    }

    @Override
    public void onNavigationDrawerItemSelected(int position) {
        // update the main content by replacing fragments

        fragmentManager = getSupportFragmentManager();

        switch (position) {
        case 0:
            fragmentManager.beginTransaction()
                    .replace(R.id.container, new HomeFragment())
                    .addToBackStack("TAG_FRAGMENT").commit();
            break;
        case 1:

            fragmentManager.beginTransaction()
                    .replace(R.id.container, new GameTabFragment())
                    .addToBackStack("TAG_FRAGMENT").commit();
            break;
        default:
            fragmentManager.beginTransaction()
                    .replace(R.id.container, new HomeFragment())
                    .addToBackStack("TAG_FRAGMENT").commit();
            break;
        }
    }

    public void onSectionAttached(int number, int gameId) {
        pos = number;
        if (gameId != 0) {
            fragmentManager = getSupportFragmentManager();
            fragmentManager
                    .beginTransaction()
                    .replace(R.id.container,
                            GameDetailFragment.newInstance(number, gameId))
                    // .addToBackStack("TAG_FRAGMENT")
                    .commit();
        }
    }

    @Override
    public void onBackPressed() {
        // TODO Auto-generated method stub
        if (pos == 0) {
            finish();
        } else {
            onNavigationDrawerItemSelected(pos);
        }
    }

    public void restoreActionBar() {
        ActionBar mActionBar = getSupportActionBar();
        mActionBar.setDisplayShowHomeEnabled(false);
        mActionBar.setDisplayShowTitleEnabled(false);
        LayoutInflater mInflater = LayoutInflater.from(this);

        View mCustomView = mInflater.inflate(R.layout.custom_actionbar, null);

        ImageView imageButton = (ImageView) mCustomView
                .findViewById(R.id.btnMenu);
        imageButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View view) {
                mNavigationDrawerFragment.openDrawer();
            }
        });

        mActionBar.setCustomView(mCustomView, new LayoutParams(
                LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
        mActionBar.setDisplayShowCustomEnabled(true);
    }
}

非常感谢您的帮助。

- sedayux

---

请使用getChildFragmentManager()代替getSupportFragmentManager()。 - Yugesh

@Yugesh：我应该把它放在哪里？因为我不能把它放在onNavigationDrawerItemSelected里面，我得到了这样的警告：“The method getChildFragmentManager() is undefined for the type MainActivity”。 - sedayux

你能添加MainActivity的代码吗？ - Yugesh

@Yugesh：我已经添加了我的MainActivity，希望你能给我一些灵感。 - sedayux

谢谢你的代码，它帮了我很多忙。thaku huni的答案解决了内容被擦除的问题。我也遇到了同样的问题。在你的TabFragment类（GameTabFragment）中，将getFragmentManager替换为getChildFragmentManager。不要使用：adapter = new TabPagerAdapter(this.getFragmentManager());而是使用：adapter = new TabPagerAdapter(this.getChildFragmentManager());这应该可以解决问题。 - Pedro Varela

Answer 1

我也曾遇到同样的问题。在你的TabFragment类（GameTabFragment）中，将getFragmentManager替换为getChildFragmentManager。

原本是: adapter = new TabPagerAdapter(this.getFragmentManager());

现在改为： adapter = new TabPagerAdapter(this.getChildFragmentManager());

这样应该就可以解决问题了。

- thaku huni

---

谢谢，它真的有效！如果您能解释一下为什么会发生这种情况，那就太完美了。 - DmRomantsov

非常感谢。在浪费了这么多时间之后，这个解决方案终于起作用了。 - ABHIMANGAL MS

Answer 2

我有3个选项卡，并且遇到了相同的问题。我使用下面的代码解决了这个问题。

pager.setOffscreenPageLimit(2);

- Tolgay Toklar

Answer 3

在 PagerFragment 的 onResume() 方法中添加以下内容：

@Override
public void onResume() {
    super.onResume();

    for (Fragment fragment : getFragmentManager().getFragments()) {
        if (fragment instanceof Tab1Fragment || fragment instanceof Tab2Fragment) {
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.detach(fragment);
            ft.attach(fragment);
            ft.commit();
        }
    }
}

- Hanoch Moreno

Answer 4

可能已经有点晚了，但我曾经也遇到过同样的问题，花费了数小时的时间，即使参考了以上所有答案，最终我还是自己解决了这个问题。我的解决方案包括以下步骤：

使用 getChildFragmentManager() 提交第一个transaction（你通常在viewpager的一个tab中的根Fragment中进行提交）。

使用 getFragmentManager() 提交其余的 transactions（用于替换嵌套的 fragments）。

这可能也是回答这个问题IllegalArgumentException: No view found for id for fragment --- ViewPager in ViewPager的方法之一。

希望这对其他人也有所帮助！

- hzitoun