Android设置图像位图问题

我正在做一个与web服务器通信并下载一些照片的项目。我希望这些照片在下载后显示在listview上，但这给我带来了一个

NullPointerException

。以下是我正在使用的代码：

   private ArrayList <HashMap<String, Object>> items;
    private static final String NAMEKEY = "bookname";
    private static final String INFOKEY = "bookprice";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.mystampii_layout);
    }
        });

        ListView listView = (ListView)findViewById(R.id.mystampii_listview);
        items = new ArrayList<HashMap<String,Object>>();
        HashMap<String, Object> hm;


        final Bitmap b = BitmapFactory.decodeFile("/sdcard/MediaCard2a44bb1f782925923195ee546e7ef395.jpg", null);
        ImageView brum = (ImageView) findViewById(R.id.main_img);
        brum.setImageBitmap(b);


        hm = new HashMap<String, Object>();
        hm.put(NAMEKEY, "Moto GP 2010");
        hm.put(INFOKEY, "98 Stampii");
        items.add(hm);

          // Define SimpleAdapter and Map the values with Row view R.layout.listbox
           SimpleAdapter adapter = new SimpleAdapter(this, items, R.layout.main_listview,
                    new String[]{NAMEKEY,INFOKEY}, new int[]{R.id.main_img,R.id.main_name, R.id.main_info});

            listView.setAdapter(adapter);
            listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    }

私有数组列表项；
私有静态最终字符串NAMEKEY=“bookname”；
私有静态最终字符串INFOKEY=“bookprice”；
@凌驾
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.mystampii_布局）；
}
});
ListView ListView=（ListView）findViewById（R.id.mystampii_ListView）；
items=newarraylist（）；
HashMap-hm；
最终位图b=BitmapFactory.decodeFile（“/sdcard/MediaCard2a44bb1f782925923195ee546e7ef395.jpg”，null）；
ImageView brum=（ImageView）findViewById（R.id.main\u img）；
brum.setImageBitmap（b）；
hm=新的HashMap（）；
hm.put（姓名钥匙，“2010年摩托车大奖赛”）；
hm.put（信息键，“98 Stampii”）；
添加项目（hm）；
//定义SimpleAdapter并使用Row view R.layout.listbox映射值
SimpleAdapter=new SimpleAdapter（此，项，R.layout.main\u列表视图，
新字符串[]{NAMEKEY，INFOKEY}，新int[]{R.id.main\u img，R.id.main\u name，R.id.main\u info}）；
setAdapter（适配器）；
listView.setChoiceMode（listView.CHOICE\u MODE\u SINGLE）；
}

我知道，为什么我会得到NullPointerException：因为我的

ImageView brum

被放置在

R.layout.main\u listview

中，我正在设置为此活动

R.layout.mystampii\u layout

的内容。我真的知道如何将SD卡中的图像设置为另一个布局中的ImageView

有什么建议可以这样做，或者如何在listview中显示从SD卡下载的图像

---

谢谢你的帮助

试试简单的代码：：

 ImageView image = (ImageView) findViewById(R.id.test_image);
        FileInputStream in;
        BufferedInputStream buf;
        try {
            in = new FileInputStream("/sdcard/test2.png");
            buf = new BufferedInputStream(in);
            Bitmap bMap = BitmapFactory.decodeStream(buf);
            image.setImageBitmap(bMap);
            if (in != null) {
            in.close();
            }
            if (buf != null) {
            buf.close();
            }
        } catch (Exception e) {
            Log.e("Error reading file", e.toString());
        }

---

实现所需功能的最佳方法是实现自定义适配器，并在适配器中使用.getView（）充气R.layout.main\u listview创建自定义适配器，如下所示：

import java.util.ArrayList;

import com.stampii.stampii.R;
import com.stampii.stampii.comm.rpc.CollectionRPCPacket;
import com.stampii.stampii.comm.rpc.UserDatabaseHelper;

import android.app.Activity;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class MyArrayAdapter extends ArrayAdapter<String> {
    private final Activity context;
    private final String[] names;
    CollectionRPCPacket rpcPacket;
    Cursor cursor;
    String title;

    public MyArrayAdapter(Activity context, String[] names) {
        super(context, R.layout.main_listview, names);
        this.context = context;
        this.names = names;
    }

    // static to save the reference to the outer class and to avoid access to
    // any members of the containing class
    static class ViewHolder {
        public ImageView imageView;
        public TextView textView,textView2;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // ViewHolder will buffer the assess to the individual fields of the row
        // layout

        ViewHolder holder;
        // Recycle existing view if passed as parameter
        // This will save memory and time on Android
        // This only works if the base layout for all classes are the same
        View rowView = convertView;
        if (rowView == null) {
            LayoutInflater inflater = context.getLayoutInflater();
            rowView = inflater.inflate(R.layout.main_listview, null, true);
            holder = new ViewHolder();
            holder.textView = (TextView) rowView.findViewById(R.id.main_name);
            holder.textView2 = (TextView) rowView.findViewById(R.id.main_info);
            holder.imageView = (ImageView) rowView.findViewById(R.id.main_img);
            rowView.setTag(holder);
        } else {
            holder = (ViewHolder) rowView.getTag();
        }
        final Bitmap b = BitmapFactory.decodeFile("/sdcard/MediaCard2a44bb1f782925923195ee546e7ef395.jpg", null);


        holder.textView.setText();
        holder.textView2.setText("");
        holder.imageView.setImageBitmap(b);


        return rowView;
    }
}

---

希望有帮助

查看throwin me异常

java.lang.ArrayIndexOutOfBoundsException

如果您实现了适配器，您可以使用getView:，以便在放置ImageView和设置所需的所有内容的位置扩大布局

ListView lv1 = (ListView)findViewById(R.id.listViewOne);
String[] names = new String[] { "ONE", "TWO", "THREE"};
lv1.setAdapter(new MyArrayAdapter(this, names));