我对 Android 开发和整体开发还比较陌生。我无法掌握 ViewPager 的语法/过程。

我有几个 ListView，我想将它们实现到 ViewPager 中。我已经加载了兼容包和所有东西。但我还没有看到任何完整的例子来说明如何做到这一点。

我通过看例子学得最好。如果有人可以发布您在其中实现此类操作的任何项目的示例，请告诉我。

问题是当我尝试启动我的 Activity 时，我在这一行得到了一个空指针异常:

listView1.setAdapter(new ArrayAdapter<Object>(this, R.layout.rowlayout, list1));

我怀疑我只是做错了。如果我不使用 ViewPager，我可以获得两个列表来显示它们的内容。所以我知道列表不为空...

编辑:

感谢 VenomM 的回答!这是我最终使用的代码，根据 VenomM 的示例稍作修改。

ViewPagerAdapter:

public class ViewPagerAdapter extends PagerAdapter implements TitleProvider
{
    private ListView listView1;
    private static String[] titles = new String[]
    {
       "Page 1",
       "Page 2",
       "Page 3",
    };
    private final Context context;

    public ViewPagerAdapter( Context context )
    {
        this.context = context;
    }

    @Override
    public String getTitle( int position )
    {
        return titles[ position ];
    }

    @Override
    public int getCount()
    {
        return titles.length;
    }

    @Override
    public Object instantiateItem(View collection, int position) {

        LayoutInflater layoutInflater = ((Activity) context).getLayoutInflater();

        listView1 = (ListView) layoutInflater.inflate(R.layout.listview1, null);

        String[] listData = null;
        MyArrayAdapter dataAdapter;

        if (position == 0) {
          listData = context.getResources().getStringArray(R.array.list1);
          dataAdapter = new MyArrayAdapter((Activity) context,
              R.layout.rowlayout, listData);
        } else if (position == 1) {
          listData = context.getResources().getStringArray(R.array.list2);
          dataAdapter = new MyArrayAdapter((Activity) context,
              R.layout.rowlayout, listData);
        } else {
          listData = context.getResources().getStringArray(R.array.list3);
          dataAdapter = new MyArrayAdapter((Activity) context,
              R.layout.rowlayout, listData);
        }

        listView1.setAdapter(dataAdapter);
        listView1.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapter, View view,
                int position, long arg3) {
              Toast.makeText(context,
                  adapter.getAdapter().getItem(position).toString(),
                  Toast.LENGTH_LONG).show();
            }
        });

        ((ViewPager) collection).addView(listView1, 0);

        return listView1;
    }


    @Override
    public void destroyItem(View collection, int position, Object view) {
        System.out.println("on destroyItem()");
        ((ViewPager) collection).removeView((ListView) view);
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        System.out.println("on isViewFromObject()");
        return view == ((ListView) object);
    }

    @Override
    public void finishUpdate( View view ) {}

    @Override
    public void restoreState( Parcelable p, ClassLoader c ) {}

    @Override
    public Parcelable saveState() {
        return null;
    }

    @Override
    public void startUpdate( View view ) {}
}

数组适配器:

public class MyArrayAdapter extends ArrayAdapter<String>{

    private Activity context = null;
    private String[] names = null;
    private int rowLayoutId;
    public MyArrayAdapter(Activity context, int textViewResourceId, String[] names) {
        super(context, textViewResourceId, names);
        this.context = context;
        this.names = names;
        this.rowLayoutId =textViewResourceId;
    }

    // static to save the reference to the outer class and to avoid access to
    // any members of the containing class
    static class ViewHolder {
        protected ImageView imageView;
        protected TextView textView;
    }

}

最佳答案

我仍然不明白为什么要用对象参数更改 Arrayadapter，如果你想让它保存字符串项。 尝试改变

new ArrayAdapter<Object>(this, R.layout.rowlayout, list1)

到

new ArrayAdapter<String>(this, R.layout.rowlayout, list1)

我使用了自定义 ArrayAdapter，对我来说一切正常。如果您成功了，请告诉我。

关于Android ViewPager 和 ListViews，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7376613/