我对 Android 开发和整体开发相对较新。我无法掌握 ViewPager 的语法/过程。
我有几个要在 ViewPager 中实现的 ListView。我已经加载了兼容性包和所有内容。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实施此类事情的任何项目的示例，请告诉我。
问题是当我尝试启动我的活动时，我在这条线上得到一个空指针异常：
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。所以我知道列表不是空的......
编辑：
感谢 VenomM 下面的回答！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 ) {}
}
阵列适配器：
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;
}
}