android - 带有 viewpager 的嵌套 fragment ，其中 viewpager 未加载 fragment

Question

我有一个正在加载 fragment 的 Activity

Home fragmentA = new Home();
        android.support.v4.app.FragmentTransaction fragmentTransactionA = getSupportFragmentManager().beginTransaction();
        fragmentTransactionA.replace(R.id.mainFrame, fragmentA);
        fragmentTransactionA.commitAllowingStateLoss();

在我的主页 fragment 中，我有一个 slidingtablayout 和 viewpager

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context="mobile.data.woises.fragment.Home">

    <mobile.data.woises.tabs.SlidingTabLayout
        android:id="@+id/sliding_tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/main_color"
        app:tabIndicatorColor="#0bbea5"/>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="0px"
        android:layout_weight="1"
        android:background="@android:color/white"/>

</FrameLayout>

我的主页 fragment 的 java 代码是这样的

public class Home extends Fragment {

    View infHome;
    SlidingTabLayout slidingTabLayout;
    ViewPager viewPager;
    private FragmentPageAdapterHome Pa;
    CharSequence Titles[] = {"Requirements", "Notification"};
    int Numboftabs = 2;

    public Home() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        infHome = inflater.inflate(R.layout.fragment_home2, container, false);

        return infHome;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        slidingTabLayout = (SlidingTabLayout) infHome.findViewById(R.id.sliding_tabs);
        viewPager = (android.support.v4.view.ViewPager) infHome.findViewById(R.id.viewpager);

        // adapter = new ViewPagerAdapter(getResources(), getChildFragmentManager());
        //  FragmentManager fragmentManager = getChildFragmentManager();
        Pa = new FragmentPageAdapterHome(getChildFragmentManager(), Titles, Numboftabs, getActivity().getApplicationContext());
        viewPager.setAdapter(Pa);
        slidingTabLayout.setSelectedIndicatorColors(Color.parseColor("#0bbea5"));
        slidingTabLayout.setDistributeEvenly(true);
        slidingTabLayout.setViewPager(viewPager);
    }

}

我的 FragmentPageAdapterHome 是这个

import android.content.Context;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.util.Log;
import android.view.ViewGroup;

import java.util.HashMap;
import java.util.Map;

import mobile.data.woises.fragment.Notification;
import mobile.data.woises.fragment.Requirements;

/*import com.example.uday.innohabit.fragments.FragA;
import com.example.uday.innohabit.fragments.FragB;
import com.example.uday.innohabit.fragments.FragC;*/


/**
 * Created by Uday on 05-11-2015.
 */
public class FragmentPageAdapterHome extends FragmentPagerAdapter {


    private Map<Integer, String> mFragmentTags;
    private FragmentManager mFragmentManager;
    private Context mContext;
    private String WoisesId;
    CharSequence Titles[];
    int NumofTabs;
    //int icons[] = {R.drawable.search,R.drawable.cart,R.drawable.quickorder};

    //String tabTitle;
    public FragmentPageAdapterHome(FragmentManager fm, CharSequence mTitles[],
                                   int mNumbOfTabsumb, Context context) {
        super(fm);


        this.Titles = mTitles;
        this.NumofTabs = mNumbOfTabsumb;


        mFragmentManager = fm;
        mFragmentTags = new HashMap<Integer, String>();
        mContext = context;

        // TODO Auto-generated constructor stub


    }


    @Override
    public Fragment getItem(int arg0) {
Log.d("FragmentPageAdapterHome","Arg="+arg0);
        switch (arg0) {
            case 0:
                Requirements requirements = new Requirements();
                return requirements;
            case 1:
                Notification notification = new Notification();
                return notification;
            default:
                break;
        }
        return null;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return Titles[position];
    }

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

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        Object obj = super.instantiateItem(container, position);
        if (obj instanceof Fragment) {
            // record the fragment tag here.
            Fragment f = (Fragment) obj;
            String tag = f.getTag();
            mFragmentTags.put(position, tag);
        }
        return obj;
    }

    public Fragment getFragment(int position) {
        String tag = mFragmentTags.get(position);
        if (tag == null)
            return null;
        return mFragmentManager.findFragmentByTag(tag);
    }
}

要求中的所有日志和通知 fragment 都显示在 Logcat 中，这意味着正在调用该函数但未显示该 fragment 请帮助我哪里出错了。我正在使用 getsupportfragmentmanager() 但有人在堆栈溢出上发布说我应该在嵌套 fragment 时使用 getChildFragmentManager() 。我该怎么办。请帮助我，我无法弄清楚是什么问题。

Answer 1

您将 ViewPagers height 设置为 0px。 layout_weight 是 LinearLayout 的一项功能，因为您使用的是 FrameLayout，所以不会显示任何内容。可能的修复:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context="mobile.data.woises.fragment.Home">

    <mobile.data.woises.tabs.SlidingTabLayout
        android:id="@+id/sliding_tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/main_color"
        app:tabIndicatorColor="#0bbea5"/>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="@android:color/white"/>

</LinearLayout>

//or:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context="mobile.data.woises.fragment.Home">

    <mobile.data.woises.tabs.SlidingTabLayout
        android:id="@+id/sliding_tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/main_color"
        app:tabIndicatorColor="#0bbea5"/>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:background="@android:color/white"/>

</FrameLayout>

另外，不要使用 px，因为您的布局在不同的屏幕上看起来会有所不同。请改用 dp(密度点)!