Daten in Listenansicht aktualisieren, nachdem Daten in der Datenbank hinzugefügt

Question

Ich habe eine Anwendung, wobei, ruft er Daten von DB und zeigt sie in einer Listenansicht, aber ich mag es aktualisieren, nachdem neue Daten in der Datenbank hinzugefügt ohne Verwendung:

Intent i = new Intent (MyActivity.this,MyActivity.class); 
startActivity (i); 

Hier ist mein Code:

public class MainActivity extends ActionBarActivity { 
//DB Class to perform DB related operations 
DBController controller = new DBController(this); 
//Progress Dialog Object 
ProgressDialog prgDialog; 
EditText userName; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    userName = (EditText) findViewById(R.id.userName); 

    //Get User records from SQLite DB 
    ArrayList<HashMap<String, String>> userList = controller.getAllUsers(); 
    // 
    if (userList.size() != 0) { 
     //Set the User Array list in ListView 
     ListAdapter adapter = new SimpleAdapter(MainActivity.this, userList, R.layout.view_user_entry, new String[]{"userId", "userName"}, new int[]{R.id.userId, R.id.userName}); 
     ListView myList = (ListView) findViewById(android.R.id.list); 
     myList.setAdapter(adapter); 
     //Display Sync status of SQLite DB 
     Toast.makeText(getApplicationContext(), controller.getSyncStatus(), Toast.LENGTH_LONG).show(); 
    } 
    //Initialize Progress Dialog properties 
    prgDialog = new ProgressDialog(this); 
    prgDialog.setMessage("Synching SQLite Data with Remote MySQL DB. Please wait..."); 
    prgDialog.setCancelable(false); 
} 

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

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    // Handle action bar item clicks here. The action bar will 
    // automatically handle clicks on the Home/Up button, so long 
    // as you specify a parent activity in AndroidManifest.xml. 
    int id = item.getItemId(); 
    //When Sync action button is clicked 
    if (id == R.id.refresh) { 
     //Sync SQLite DB data to remote MySQL DB 
     syncSQLiteMySQLDB(); 
     return true; 
    } 
    return super.onOptionsItemSelected(item); 
} 

//Add User method getting called on clicking (+) button 
public void addUser(View view) { 
    Intent objIntent = new Intent(getApplicationContext(), NewUser.class); 
    startActivity(objIntent); 
} 

public void syncSQLiteMySQLDB() { 
    //Create AsycHttpClient object 
    AsyncHttpClient client = new AsyncHttpClient(); 
    RequestParams params = new RequestParams(); 
    ArrayList<HashMap<String, String>> userList = controller.getAllUsers(); 

    if (userList.size() != 0) { 
     if (controller.dbSyncCount() != 0) { 
      prgDialog.show(); 
      params.put("usersJSON", controller.composeJSONfromSQLite()); 
      client.post("http://192.168.2.4:9000/sqlitemysqlsync/insertuser.php", params, new AsyncHttpResponseHandler() { 
       @Override 
       public void onSuccess(String response) { 
        System.out.println(response); 
        prgDialog.hide(); 
        try { 
         JSONArray arr = new JSONArray(response); 
         System.out.println(arr.length()); 
         for (int i = 0; i < arr.length(); i++) { 
          JSONObject obj = (JSONObject) arr.get(i); 
          System.out.println(obj.get("id")); 
          System.out.println(obj.get("status")); 
          controller.updateSyncStatus(obj.get("id").toString(), obj.get("status").toString()); 
         } 
         Toast.makeText(getApplicationContext(), "DB Sync completed!", Toast.LENGTH_LONG).show(); 
        } catch (JSONException e) { 
         // TODO Auto-generated catch block 
         Toast.makeText(getApplicationContext(), "Error Occured [Server's JSON response might be invalid]!", Toast.LENGTH_LONG).show(); 
         e.printStackTrace(); 
        } 
       } 

       @Override 
       public void onFailure(int statusCode, Throwable error, 
             String content) { 
        // TODO Auto-generated method stub 
        prgDialog.hide(); 
        if (statusCode == 404) { 
         Toast.makeText(getApplicationContext(), "Requested resource not found", Toast.LENGTH_LONG).show(); 
        } else if (statusCode == 500) { 
         Toast.makeText(getApplicationContext(), "Something went wrong at server end", Toast.LENGTH_LONG).show(); 
        } else { 
         Toast.makeText(getApplicationContext(), "Unexpected Error occcured! [Most common Error: Device might not be connected to Internet]", Toast.LENGTH_LONG).show(); 
        } 
       } 
      }); 
     } else { 
      Toast.makeText(getApplicationContext(), "SQLite and Remote MySQL DBs are in Sync!", Toast.LENGTH_LONG).show(); 
     } 
    } else { 
     Toast.makeText(getApplicationContext(), "No data in SQLite DB, please do enter User name to perform Sync action", Toast.LENGTH_LONG).show(); 
    } 
} 





/** 
* Called when Save button is clicked 
* @param view 
*/ 
public void addNewUser(View view) { 
    HashMap<String, String> queryValues = new HashMap<String, String>(); 
    queryValues.put("userName", userName.getText().toString()); 
    if (userName.getText().toString() != null 
      && userName.getText().toString().trim().length() != 0) { 
     controller.insertUser(queryValues); 

    } else { 
     Toast.makeText(getApplicationContext(), "Please enter User name", 
       Toast.LENGTH_LONG).show(); 
    } 
} 

@Override 
protected void onResume() { 
    super.onResume(); 
} 
} 

Answer 1

Anruf clear() auf dem Adapter dann notifyDatasetChanged(), dies wird in der Liste der alten Daten loszuwerden. Zu diesem Zeitpunkt können Sie Ihren Datenbank-Cursor neu laden.