android - 无法启动 Activity ComponentInfo :java. lang.RuntimeException:您的内容必须有一个 ListView，其 id 属性为 'android.R.id.list'

Question

我刚开始使用 json 。以 json 格式从 mysql 获取数据显示在 listview android 上。 Caused by: java.lang.RuntimeException: 你的内容必须有一个 ListView，它的 id 属性是 'android.R.id.list'

public class MainActivity extends ListActivity {
private ProgressDialog pDialog;

// URL to get contacts JSON
private static String url= "http://127.0.0.1/bloodRequest/data.php";
// JSON Node names
private static final String TAG_CONTACTS = "requests ";
private static final String TAG_NAME = "User_name";
private static final String TAG_BLOCKNO = "user_block_no";
private static final String TAG_ADDRESS = "user_stree_address";
private static final String TAG_CITY = "user_city_village";
private static final String TAG_TALUKA = "user_taluka";
private static final String TAG_DISTRICT = "user_district";
private static final String TAG_BLOOD_TYPE = "blood_type";
private static final String TAG_CREATE_DATE = "createdate";
private static final String TAG_PHONE = "user_mobile";

// contacts JSONArray
JSONArray requests= null;

// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ListView list = getListView();
    new GetContacts().execute();
}
/**
 * Async task class to get json by making HTTP call
 * */
private class GetContacts extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(MainActivity.this);
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);
        pDialog.show();

    }

    @Override
    protected Void doInBackground(Void... arg0) {
        // Creating service handler class instance
        ServiceHandler sh = new ServiceHandler();

        // Making a request to url and getting response
        String jsonStr = sh.makeServiceCall(url, ServiceHandler.POST);

        Log.d("Response: ", "> " + jsonStr);

        if (jsonStr != null) {
            try {
                JSONObject jsonObj = new JSONObject(jsonStr);

                // Getting JSON Array node
                requests = jsonObj.getJSONArray(TAG_CONTACTS);

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


                    String name = c.getString(TAG_NAME);
                    String blockno = c.getString(TAG_BLOCKNO);
                    String address = c.getString(TAG_ADDRESS);
                    String city = c.getString(TAG_CITY);
                    String district=c.getString(TAG_DISTRICT);
                    String taluk=c.getString(TAG_TALUKA);
                    String blodtype=c.getString(TAG_BLOOD_TYPE);
                    String phone=c.getString(TAG_PHONE);
                    String createdate=c.getString(TAG_CREATE_DATE);

                    // tmp hashmap for single contact
                    HashMap<String, String> requests1  = new HashMap<String, String>();

                    // adding each child node to HashMap key => value

                    requests1  .put(TAG_NAME, name);
                    requests1  .put(TAG_BLOCKNO, blockno);
                    requests1  .put(TAG_ADDRESS, address);
                    requests1 .put(TAG_CITY, city);
                    requests1 .put(TAG_TALUKA, taluk);
                    requests1 .put(TAG_DISTRICT, district);
                    requests1 .put(TAG_BLOOD_TYPE, blodtype);
                    requests1 .put(TAG_PHONE, phone);
                    requests1 .put(TAG_CREATE_DATE, createdate);

                    // adding contact to contact list
                    contactList.add( requests1 );
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        } else {
            Log.e("ServiceHandler", "Couldn't get any data from the url");
        }

        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        // Dismiss the progress dialog
        if (pDialog.isShowing())
            pDialog.dismiss();
        /**
         * Updating parsed JSON data into ListView
         * */

        ListAdapter adapter = new SimpleAdapter(
                MainActivity.this, contactList,
                R.layout.item_list,
                new String[] { TAG_NAME, TAG_BLOCKNO,TAG_ADDRESS,TAG_CITY,TAG_TALUKA,TAG_DISTRICT,TAG_BLOOD_TYPE,TAG_PHONE,TAG_CREATE_DATE},
                new int[] { R.id.name, R.id.blono, R.id.street,R.id.city,R.id.taluk,R.id.distr,R.id.btype,R.id.phno,R.id.crdate });

        setListAdapter(adapter);
    }

}
}

Answer 1

使用 android:id="@android:id/list" 添加到您的 activity_main ListView

如果您在 Activity 布局中使用 ListActivity，您应该添加:

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