Question

我在我的活动中使用Sectioned List，ListActivity 但现在因为我需要将Actionbar添加到此活动，所以我不能在这里使用ListActivity。所以我试图使用ListView。但我没有得到如何将适配器设置为Listview。因为我需要设置用于SectionedListView的自定义适配器。但是当我将它用于简单的ListView时，它会给出NullPointer异常。我浪费了足够的时间请帮帮我。

这是ListView的xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >
    </ListView>

</LinearLayout>

and this is the adapter used for (ListActivity).


public class EntryAdapter extends ArrayAdapter<Item> {

    private Context context;
    private ArrayList<Item> items;
    private LayoutInflater vi;
    private ImageDownloader mImageDownloader;
    public EntryAdapter(Context context,ArrayList<Item> items, ImageDownloader mImageDownloader) {
        super(context,0, items);
        this.context = context;
        this.items = items;
        vi = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        this.mImageDownloader = mImageDownloader;
    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View v = convertView;
        Log.v("position in entry adapter", ""+position);

        final Item i = items.get(position);
        if (i != null) {
            if(i.isSection()){
                SectionItem si = (SectionItem)i;
                v = vi.inflate(R.layout.list_item_section, null);

                v.setOnClickListener(null);
                v.setOnLongClickListener(null);
                v.setLongClickable(false);

                final TextView sectionView = (TextView) v.findViewById(R.id.list_item_section_text);
                sectionView.setText(si.getTitle());
            }else{
                EntryItem ei = (EntryItem)i;
                v = vi.inflate(R.layout.list_item_entry, null);
                final TextView title = (TextView)v.findViewById(R.id.list_item_entry_title);
                final TextView subtitle = (TextView)v.findViewById(R.id.list_item_entry_summary);
                final ImageView cat_icon = (ImageView)v.findViewById(R.id.category_icon);
                final ImageView channel_icon = (ImageView)v.findViewById(R.id.channel_icon);
                if (title != null) 
                    title.setText(ei.title);
                if(subtitle != null)
                    subtitle.setText(ei.subtitle);
                if(cat_icon != null)
                {
                    if(ei.catIcon != null)
                        cat_icon.setImageBitmap(ei.catIcon);
                    else
                        cat_icon.setVisibility(View.INVISIBLE);
                }
                if(channel_icon !=null)
                {
                    if(ei.url != null)
                    {
                        mImageDownloader.download(ei.url,channel_icon);
                        Log.v("url in adapter", ei.url);
                    }
                    else
                        channel_icon.setVisibility(View.INVISIBLE);
                }
            }
        }
        return v;
    }


}



mList = (ListView) findViewById(R.id.list);

EntryAdapter adapter = new EntryAdapter(this, items, mImageDownloader);
        mList.setAdapter(adapter);
        mList.setOnItemClickListener(this);

由于 MAHAVEER。

Answer 1

更改将ListActivity扩展为Activity的类，

需要执行的操作

1。）使用Activity而不是ListActivity扩展您的类

2.。）将xml中ListView的ID从@android:id/list更改为@+id/your_listview

3.）找到使用
在xml中声明的ListView实例

ListView your_listview = (ListView)findViewById(R.id.your_listview);

4.。）使用适配器， your_listview.setAdapter（适配器）;

Answer 2

试试这个，

1）将ListView的ID更改为android:id="@+id/list"。

2）而不是扩展ListActivity扩展Activity。

如何为SectionedListView设置ListView而不是ListActivity

2 个答案: