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我是 Android 编码的新手。我使用 SimpleAdapter 编写了一个多行列表，但没有显示文本。如果我切换到硬编码的哈希列表，文本会显示在屏幕上。为了确保我的变量实际上包含文本，我使用 Log.e 打印了它的内容。

我可能做错了什么？

public class AndroidListViewActivity extends ListActivity { 

@Override
protected void onCreate(Bundle savedInstanceState) {
    ListParse mytask;

    super.onCreate(savedInstanceState);

    mytask = new ListParse();
    mytask.execute();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    // getMenuInflater().inflate(R.layout.activity_main, menu);
    return true;
}

private class ListParse extends AsyncTask<URL, Integer, Long> {
    // url to make request
    private static final String url = "http://api.androidhive.info/contacts/";

    // JSON Node names
    private static final String TAG_CONTACTS = "contacts";
    private static final String TAG_ID = "id";
    private static final String TAG_NAME = "name";
    private static final String TAG_EMAIL = "email";
    private static final String TAG_PHONE = "phone";
    private static final String TAG_PHONE_MOBILE = "mobile";
    // create the grid item mapping
    String[] from = new String[] { "TAG_NAME", "TAG_EMAIL", "TAG_PHONE_MOBILE" };
    int[] to = new int[] { R.id.list_name, R.id.list_email, R.id.list_mobile };

    // contacts JSONArray
    JSONArray contacts = null;

    // Hashmap for ListView
    ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();      

    @Override
    protected void onPostExecute(Long result) {
        Iterator<HashMap<String, String>> entry = contactList.iterator();
        while (entry.hasNext()){
            Log.e("Debug Info", "We have " + entry.next());
        }

        SimpleAdapter adapter = new SimpleAdapter(AndroidListViewActivity.this, contactList,
                R.layout.list_item, from, to);
        setListAdapter(adapter);
    }

    @Override
    protected Long doInBackground(URL... arg0) {

        // Creating JSON Parser instance
        JSONParser jParser = new JSONParser();

        // getting JSON string from URL
        JSONObject json = jParser.getJSONFromUrl(url);

        try {
            // Getting Array of Contacts
            contacts = json.getJSONArray(TAG_CONTACTS);

            // looping through All Contacts
            for (int i = 0; i < contacts.length(); i++) {
                JSONObject c = contacts.getJSONObject(i);

                // Storing each json item in variable
                String id = c.getString(TAG_ID);
                String name = c.getString(TAG_NAME);
                String email = c.getString(TAG_EMAIL);
                // Phone number is again JSON Object
                JSONObject phone = c.getJSONObject(TAG_PHONE);
                String mobile = phone.getString(TAG_PHONE_MOBILE);
                // creating new HashMap
                HashMap<String, String> map = new HashMap<String, String>();

                // adding each child node to HashMap key => value
                map.put(TAG_ID, id);
                map.put(TAG_NAME, name);
                map.put(TAG_EMAIL, email);
                map.put(TAG_PHONE_MOBILE, mobile);                  

                // adding HashList to ArrayList
                contactList.add(map);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

}

}

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