Question

我有一个应用程序，它从数据库中检索数据并将其显示在列表视图中，但我希望在将新数据添加到数据库之后刷新它而不使用：

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

这是我的代码：

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

在适配器上调用clear（）然后调用notifyDatasetChanged（），这将清除列表中的旧数据。此时您可以重新加载数据库游标。

将数据添加到数据库后，在listview中刷新数据

1 个答案: