Question

我正在尝试使用文本和图片创建Listview。图像从URL显示。我从数据库中提取文本和图像URL，并将其存储在ArrayList＆lt; HashMap＆lt;字符串，字符串＆gt;＆gt;。
在我的代码下面但没有工作。

适配器出了问题，但我无法找到问题有人能帮帮我吗？谢谢。

活动：

public class Test extends Activity {

ListView list;
LazyAdapter adapter;
String result;
ArrayList<HashMap<String, String>> listItem = new ArrayList<HashMap<String, String>>();
HashMap<String, String> map;

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

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


    try{
                    DBConnection DBC = new DBConnection();
                    String URL = "http://10.0.2.2/Android.php";
        DBC.DBConnection2(URL);
        result = DBC.dd.getResult();
    }catch (Exception e) {
                    Toast.makeText(getApplicationContext(), "Erreur BD access", Toast.LENGTH_LONG).show();
    }
    try{
        JSONArray jArray = new JSONArray(result);
        JSONObject json_data=null;
        for(int j=0;j<jArray.length();j++){
            json_data = jArray.getJSONObject(j);
            String name = json_data.getString("Name");
            String title = json_data.getString("Title");
            String logo = json_data.getString("Logo");

            map = new HashMap<String, String>();
                map.put("name", name);
                map.put("title", title);
                map.put("img", logo);

                listItem.add(map);        
        }

    }catch (JSONException e1) {
        e1.printStackTrace();
    }


    adapter=new LazyAdapter(this, listItem);
    list.setAdapter(adapter);


}

}

适配器：

public class LazyAdapter extends BaseAdapter {

private Activity activity;
private ArrayList<HashMap<String, String>> data;
private static LayoutInflater inflater=null;
public ImageLoader imageLoader; 

public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> list) {
    activity = a;
    data=list;
    inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    imageLoader=new ImageLoader(activity.getApplicationContext());


}

public int getCount() {
    return data.size();
}
public Object getItem(int position) {
    return position;
}

public long getItemId(int position) {
    return position;
}



public View getView(int position, View convertView, ViewGroup parent) {

    View vi=convertView;
    if(convertView==null)
        vi = inflater.inflate(R.layout.item, null);
    TextView text=(TextView)vi.findViewById(R.id.text);;
    ImageView image=(ImageView)vi.findViewById(R.id.image);

    try  {
    HashMap<String, String> ma = data.get(position);
        for(Entry<String, String> mapEntry: ma.entrySet()) {
            String key = mapEntry.getKey();
            String value = mapEntry.getValue();
            if (key.equals("name")) text.setText(value);
            if (key.equals("img"))  imageLoader.DisplayImage(value, image); 
        }

    }catch (Exception e){
        e.printStackTrace();
    }
    return vi;
}

}

日志

06-03 02:34:33.292: E/AndroidRuntime(747): FATAL EXCEPTION: main
06-03 02:34:33.292: E/AndroidRuntime(747): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.fedorvlasov.lazylist/com.fedorvlasov.lazylist.Test}: java.lang.NullPointerException
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.os.Handler.dispatchMessage(Handler.java:99)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.os.Looper.loop(Looper.java:137)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.app.ActivityThread.main(ActivityThread.java:4745)
06-03 02:34:33.292: E/AndroidRuntime(747):  at java.lang.reflect.Method.invokeNative(Native Method)
06-03 02:34:33.292: E/AndroidRuntime(747):  at java.lang.reflect.Method.invoke(Method.java:511)
06-03 02:34:33.292: E/AndroidRuntime(747):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-03 02:34:33.292: E/AndroidRuntime(747):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-03 02:34:33.292: E/AndroidRuntime(747):  at dalvik.system.NativeStart.main(Native Method)
06-03 02:34:33.292: E/AndroidRuntime(747): Caused by: java.lang.NullPointerException
06-03 02:34:33.292: E/AndroidRuntime(747):  at com.fedorvlasov.lazylist.Test.onCreate(Test.java:84)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.app.Activity.performCreate(Activity.java:5008)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
06-03 02:34:33.292: E/AndroidRuntime(747):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
06-03 02:34:33.292: E/AndroidRuntime(747):  ... 11 more

此处指定的行：

Caused by: java.lang.NullPointerException at com.fedorvlasov.lazylist.Test.onCreate(Test.java:84)

是

list.setAdapter(adapter);

Answer 1

我最好的猜测是list布局中不存在ID为test.xml的ListView。您可以发布test.xml的内容吗？

ListView中的错误与来自url的文本和图像

1 个答案: