java-在ViewPager中更新列表视图的正确方法？

我的应用程序中的片段中有一个ViewPager.在ViewPager中,我有6个列表视图,它们从中央数据源(一个Schedule)中提取其数据,然后从每个列表视图中提取“天数列表”.现在,我试图通过更改存储在我的PagerAdapter类中的日程表来更新此日程表对象,然后更新用作所有列表视图的适配器的ArrayAdapter.切换到一个列表视图后,将使用正确的数据创建一个新的阵列适配器.

不幸的是,这根本不起作用.我在应用程序生命周期的任何时候都看不到任何数据.所以我假设我在将数据连接到ViewPager时发生了根本性的错误…

我到过网上,读过所有片段内容,很多视图寻呼机内容…
有人知道这样做的正确方法吗？

这是我的DayAdapter(ViewPagerADapter)的代码

public final class DayAdapter extends PagerAdapter {

    //~Data Fields----------------------------------------//
    /**
     * The list adapter that the current list is being handed to.
     */
    private Schedule schedule;
    /**
     * The current index of the day that is to be displayed.
     */
    private int currentIndex;
    /**
     * ArrayAdpter to be used to connect data to all of the list views.
     */
    private ArrayAdapter<Course> adapter;

    //~Constructors---------------------------------------//
    /**
     * Constructor for the DayAdapter implementation of PagerAdapter. Takes in a
     * Schedule object which is to be the data backing of the views displayed.
     * 
     * @param theSChedule the Schedule object that is the backing for the ListViews.
     */
    public DayAdapter(Schedule theSchedule) {

        schedule = theSchedule;
        currentIndex = schedule.getTodayIndex();
    }

    //~Methods--------------------------------------------//
    public void setSchedule(Schedule theSchedule) {

        schedule = theSchedule;

        adapter.clear();
        adapter.add(schedule.getDay(currentIndex).getList().get(0));
        adapter.notifyDataSetChanged();
    }

    @Override
    public Object instantiateItem(ViewGroup container, int index) {

        LayoutInflater inflater = (LayoutInflater) container.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View layout = inflater.inflate(R.layout.schedule_list_view, null);

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

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

        //TEST CODE!!!! This does not yield any sort data items in the list views!?
        adapter.add(new Course("test", "test", "test", "test", "test", "test", "test"));

        currentIndex = index;

        ((ViewPager) container).addView(layout);

        return layout;
    }

    @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 == object;
    }
}

解决方法:

如果这是InstantiateItem方法的完整代码,则通常在列表中看不到任何数据.您将名为R.layout.schedule_list_view的布局文件充气(最有可能在其中拥有一个ListView),并在相同的InstantIateItem方法中创建一个独立的ListView小部件来设置数据.由于数据绑定到不在布局文件中的ListView,因此您看不到任何内容,因为原始ListView保持为空.

解决方案是要么在充气布局(R.layout.schedule_list_view)中的ListView上设置数据(如果有),要么将创建的带有数据的ListView添加到充气布局(layout(这是一个View,所以您可以将其强制转换为ViewGroup或ViewGroup的子类).

标签：viewpagerindicator,android-fragments,android-viewpager,java,android
来源： https://codeday.me/bug/20191127/2076174.html