Question

我成功获取了json数据并已在listview中显示它。现在我的要求是在点击添加按钮时在列表中一次设置一个条目。

以下是我将数据设置为listview的主要活动

public class MainActivity extends ListActivity { 
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "";

// JSON Node names
private static final String TAG_DATA = "data";
private static final String TAG_OWNER = "owner";
private static final String TAG_ID = "id";
private static final String TAG_LOGIN = "login";

// contacts JSONArray
JSONArray data = null;

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



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

    dataList = new ArrayList<HashMap<String, String>>();

    ListView lv = getListView();

    // Listview on item click listener
    lv.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id1) {
            // TODO Auto-generated method stub

            // getting values from selected ListItem
            String login = ((TextView) view.findViewById(R.id.login))
                        .getText().toString();
            String id = ((TextView) view.findViewById(R.id.id))
                        .getText().toString();

             // Starting single contact activity
             Intent in = new Intent(getApplicationContext(),
                       SingleContactActivity.class);

            in.putExtra(TAG_ID, id);
            in.putExtra(TAG_LOGIN, login);

            startActivity(in);

        }
    });

    lv.setOnItemLongClickListener(new OnItemLongClickListener() {

        public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
                int pos, long id) {
            // TODO Auto-generated method stub
            Log.v("long clicked","pos: " + pos);
            removeItemFromList(pos);   
            return true;
        }

        private void removeItemFromList(int pos) {
            // TODO Auto-generated method stub
            final int deletePosition = pos;

               AlertDialog.Builder alert = new AlertDialog.Builder(MainActivity.this);

               alert.setTitle("Delete");
               alert.setMessage("Do you want delete this item?");
               alert.setPositiveButton("YES", new OnClickListener() {

                   @Override
                   public void onClick(DialogInterface dialog, int which) {
                       // TOD  Auto-generated method stub

                           // main code on after clicking yes
                           dataList.remove(deletePosition);
                           setListAdapter(getListAdapter());
                   }
               });
               alert.setNegativeButton("CANCEL", new OnClickListener() {
                   @Override
                   public void onClick(DialogInterface dialog, int which) {
                       // TODO Auto-generated method stub
                       dialog.dismiss();
                   }
               });

               alert.show();
        }
    });
    // Calling async task to get json
    new GetData().execute();
}



/**
 * Async task class to get json by making HTTP call
 * */
private class GetData 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.GET);

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

        if (jsonStr != null) {
            try {
                JSONArray json = new JSONArray(jsonStr);

                Log.d("in json object block", jsonStr);

                // looping through All Contacts
                for(int i=0;i<json.length();i++){                        
                    HashMap<String, String> map = new HashMap<String, String>();    
                    JSONObject e = json.getJSONObject(i);
                    // adding contact to contact list
                    JSONObject  owner = e.getJSONObject("owner");
                  //  map.put("id",  String.valueOf(i));
                    map.put("login", "Login is:" + owner.getString("login"));
                    map.put("id", "ID is: " +  owner.getString("id"));
                   // map.put("owner", "OWNER is" + e.getString("") );
                    dataList.add(map);
                }
            } 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, dataList,
                R.layout.list_item, new String[] { TAG_OWNER, TAG_LOGIN,
                        TAG_ID }, new int[] { R.id.owner,
                        R.id.login, R.id.id });
       setListAdapter(adapter);

       }
     }


}

Answer 1

在主布局上创建一个按钮。为按钮实现onclicklistener并在onlick方法中调用populateListView（）。

创建一个新列表。单击按钮时，将项目添加到新列表。调用notifydatasetchanged（）。 单击按钮时，检查项目是否已添加到新列表中。在适配器中使用新创建的列表，以便每次添加新项目。

由于

从url获取数据并在android中按下按钮时将其显示在现有列表中

1 个答案: