android - fragment 中的 ViewPager 不起作用

Question

所以我有一个带有 3 个 actionbar.Tab 的应用程序，它们在 3 个 fragment 之间切换。在其中两个 fragment 中，我需要有一个在大约 6 个 ListView 之间切换的 ViewPager。问题是我试图让它工作的 fragment 显示页面只显示黑色......总是......我已经确认我可以显示其他东西(我试着让我的 SherlockFragment 成为 SherlockListFragment 我可以在其中显示数据)。所以问题只限于我的适配器和我的 ViewPager，以及将它们放置到位的代码。哦，我还应该提到我正在使用 ActionBarSherlock 和(尝试)ViewPagerIndicator。我已正确导入(最终)。

所以这是我的 fragment 的代码:

import vt.finder.schedule.Schedule;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import com.actionbarsherlock.app.SherlockFragment;
import com.viewpagerindicator.TitlePageIndicator;


public class FreeTimeFragment extends SherlockFragment {

//~Data Fields--------------------------------------------
/**
 * Adapter used for swiping between days.
 */
private ViewPager dayPage;
/**
 * The DayAdapter that is used to switch between course Lists for each day for the listView.
 */
private DayAdapter dayAdapt;


//~Constructors--------------------------------------------
@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    View view = onCreateView(getLayoutInflater(savedInstanceState), null, savedInstanceState);

    LinearLayout layout = (LinearLayout) view.findViewById(R.id.linear_layout);
    dayPage = (ViewPager) layout.findViewById(R.id.free_time_day_pager);

    Schedule freeTime = getArguments().getParcelable("freeTime");

    dayAdapt = new DayAdapter(freeTime);
    //Bind the title indicator to the adapter
    TitlePageIndicator titleIndicator = (TitlePageIndicator) layout.findViewById(R.id.titles);
    dayPage.setAdapter(dayAdapt);
    titleIndicator.setViewPager(dayPage);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)     {

    View view = inflater.inflate(R.layout.free_time_fragment_layout, container, false);
    return view;
}
}

这是我的适配器的代码:

import vt.finder.schedule.Course;
import vt.finder.schedule.Schedule;
import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;


/**
 * PageAdapter class, provides functionality for switching between days of
 * the week.
 * 
 *
 */
public final class DayAdapter extends PagerAdapter {

    //~Data Fields----------------------------------------//
    /**
     * The list adapter that the current list is being handed to.
     */
    private Schedule schedule;

    //~Constructors---------------------------------------//
    public DayAdapter(Schedule theSchedule) {

        schedule = theSchedule;
    }

    //~Methods--------------------------------------------//
    @Override
    public Object instantiateItem(ViewGroup container, int index) {

        ListView view = new ListView(container.getContext());

        view.setAdapter(new ArrayAdapter<Course>(container.getContext(), 
                        R.layout.list_view_child, schedule.getDay(curIndex).getList()));

        ((ViewPager) container).addView(view, 0);

        return container;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {

        ViewPager pager = (ViewPager) container;
        View view = (View) object;
        pager.removeView(view);
    }

    /**
     * Gets the pageTitle, which is the name of the day that is at position.
     * 
     * @param position the index of the day selected.
     * @return the name of the day the index refers to.
     */
    @Override
    public CharSequence getPageTitle(int position) {

        return schedule.getDay(position).getThisDay();
    }

    @Override
    public int getCount() {

        return 6;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {

        return view == (View) object;
    }
}

这是我的 fragment 布局的 xml 文件:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" 
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" 
    android:weightSum="1"
    android:id="@+id/linear_layout">

    <com.viewpagerindicator.TitlePageIndicator
        android:id="@+id/titles"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1.09" />

    <android.support.v4.view.ViewPager
        android:id="@+id/free_time_day_pager"
        android:layout_width="fill_parent"
        android:layout_height="284dp" />

    <RelativeLayout
        android:id="@+id/relativeLayout1"
        android:layout_width="match_parent"
        android:layout_height="52dp"
        android:layout_weight="0.07" >

        <Button
            android:id="@+id/getScheduleButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true"
            android:onClick="getScheduleClicked"
            android:text="@string/get_schedule" />

        <Button
            android:id="@+id/compareWithFriends"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignBottom="@+id/getScheduleButton"
            android:layout_alignParentRight="true"
            android:layout_toRightOf="@+id/getScheduleButton"
            android:onClick="compareWithFriendsClicked"
            android:text="@string/compare_with_a_friend" />

    </RelativeLayout>

</LinearLayout>

而且我想我应该简要地提一下，Schedule 包含 Day 对象，而 Day 对象包含要显示的类(class)列表。所有这些代码绝对有效，我已经使用了几个月。

Answer 1

嘿，我自己想出来了，我正在使用 ViewPager 和 FragmentPagerAdapter 一起制作画廊......!

我添加了

@Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            // TODO Auto-generated method stub

                FragmentManager manager = ((Fragment) object).getFragmentManager();
                FragmentTransaction trans = manager.beginTransaction();
                trans.remove((Fragment) object);
                trans.commit();

            super.destroyItem(container, position, object);
        }

我的 FragmentPagerAdapter 删除 View 以避免开销。! :-)