Develop Reference

get TextView from another class

I want to display this textview "txtCalculate" which comes from the class CustomerMapActivity which is displayed in the activity_map_customer layout in another layout which is activity_bon_de_commande, of the class BonDeCommande.
the problem is I don't know how to do it
I'm new to java programming
thank you
public void readValues(){
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query lastQuery = ref.child("ride_info").orderByKey().limitToLast(1);
lastQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()){
double value0_float = ds.child("pickup").child("lat").getValue(Double.class);
double value1_float = ds.child("pickup").child("lng").getValue(Double.class);
double value2_float = ds.child("destination").child("lat").getValue(Double.class);
double value3_float = ds.child("destination").child("lng").getValue(Double.class);
String pickupLat = String.valueOf(value0_float);
String pickupLng = String.valueOf(value1_float);
String destiLat = String.valueOf(value2_float);
String destiLng = String.valueOf(value3_float);
String requestUrl=null;
try {
requestUrl = "https://maps.googleapis.com/maps/api/directions/json?"+
"mode=driving&"
+"transit_routing_preference=less_driving&"
+"origin="+pickupLat+","+pickupLng+"&"
+"destination="+destiLat+","+destiLng+"&"
+"key="+getResources().getString(R.string.google_maps_key);
Log.e("LINK",requestUrl);
mService.getPath(requestUrl).enqueue(new Callback<String>() {
#Override
public void onResponse(Call<String> call, Response<String> response) {
try {
JSONObject jsonObject = new JSONObject(response.body().toString());
JSONArray routes = jsonObject.getJSONArray("routes");
JSONObject object = routes.getJSONObject(0);
JSONArray legs = object.getJSONArray("legs");
JSONObject legsObject = legs.getJSONObject(0);
//Get distance
JSONObject distance = legsObject.getJSONObject("distance");
String distance_text = distance.getString("text");
//use regex to extract double from string
//This regex will remove all text not digit
Double distance_value= Double.parseDouble(distance_text.replaceAll("[^0-9\\\\.]+",""));
//Get Time
JSONObject time = legsObject.getJSONObject("duration");
String time_text = time.getString("text");
Integer time_value = Integer.parseInt(time_text.replaceAll("\\D+",""));
String final_calculate = String.format("%.2f €",
TypeObject.getPrice(distance_value,time_value));
HERE -----> txtCalculate.setText(final_calculate);
} catch (JSONException e) {
e.printStackTrace();
}
}
#Override
public void onFailure(Call<String> call, Throwable t) {
mCurrentRide.cancelRide();
endRide();
}
});
}
catch (Exception ex)
{
ex.printStackTrace();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
mCurrentRide.cancelRide();
endRide();
}
});
}
screenshot of my screen

You need to Create an Interface with an update method, declare in your Activity and after, pass as parameter to your handler object that gets the data.
Don't forget If you're getting the data in a different Thread, you need to update your views always in an UI Thread or in the Main Thread.
Here Follow some example code:
Your Activity or Fragment
public class MainActivity extends AppCompatActivity
implements UpdateViewCallback { // implement the interface here
private TextView textView = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
textView = findViewById(R.id.textView);
// Pass the interface in your Object that makes the async work
final AsyncWork asyncWork = new AsyncWork(this);
// Running
Thread thread = new Thread(asyncWork);
thread.start();
}
/**
* UpdateViewCallback
* #param result
*/
#Override
public void updateView(final String result) {
// Always update View on MainThread or an UI Thread, or else issues will start to happening
this.runOnUiThread(new Runnable() {
public void run() {
// Check if View is null since you're updating in a thread async
if (textView != null) {
textView.setText(result);
}
}
});
}
}
Your Interface:
public interface UpdateViewCallback {
void updateView(String result);
}
Your Object to handle the Async Work:
public class AsyncWork implements Runnable {
private UpdateViewCallback updateViewCallback;
public AsyncWork(UpdateViewCallback updateViewCallback) {
this.updateViewCallback = updateViewCallback;
}
/**
* Async Work here
*/
#Override
public void run() {
// Do some Work and after update using the interface you passed in the constructor
updateViewCallback.updateView("This is a test");
}
}

server connection thread too late than onCreate

I'm making app which get server data from mvc spring server.
If client login success in main Activity, app try to get data from server, and use list view show data in next activity.
It works clear in first login, but when I turn back on main Activity, and try login again, next activity doesn't show anything.
I used logs to find problem and I found that when client login again, next activity's onCreate() and onResume() works too fast. My app uses thread and get data from server, logs says after onCreate and onResume works and my thread get data from server.
So this is my problem
1 App uses thread to get data from server
2 First try works but after thread is too late than onResume and onCreate in activity
3 should I have to make thread more fast? or use flags or something make onCreate and onResume works after thread works end? or does my code have problems?
This is my activity which show data from server
public class ServerListActivity extends AppCompatActivity {
public static ArrayList<ServerListItem> serverListItemArrayList;
public static ArrayList<ServerListItem> scrollEventServerListItemList;
public TextView serverListInfoTextView;
private ProgressBar progressBar;
private boolean lockListView;
private boolean isThisLastItemVisibleFlag;
private ServerListViewAdapter serverListViewAdapter;
private int currentPageNum;
public Handler msgHandler;
#Override
protected void onCreate(Bundle savedInstanceState) {
lockListView = false; // scroll event
currentPageNum = 0; // scroll event
isThisLastItemVisibleFlag = false; // scroll event
scrollEventServerListItemList = new ArrayList<>();
serverListItemArrayList = new ArrayList<>();
msgHandler = new Handler();
super.onCreate(savedInstanceState);
ServerListManager serverListManager = new ServerListManager(msgHandler);
serverListManager.getServerList();
setContentView(R.layout.activity_server_list);
ImageButton turnBackBtn = findViewById(R.id.turn_back_btn);
serverListInfoTextView = findViewById(R.id.server_list_Info);
ListView serverListView = findViewById(R.id.server_list_view);
progressBar = findViewById(R.id.progressBar);
serverListViewAdapter = new ServerListViewAdapter(scrollEventServerListItemList, R.layout.server_list_item, getApplicationContext());
serverListView.setAdapter(serverListViewAdapter);
progressBar.setVisibility(View.GONE);
serverListView.setTranscriptMode(ListView.TRANSCRIPT_MODE_NORMAL);
System.out.println(serverListItemArrayList.size());
setServerListInfo(serverListItemArrayList);
and this is my thread
public class ServerListManager {
private final static int SERVER_PROBLEM = 666;
private Handler handler;
public ServerListManager(Handler handler) {
this.handler = handler;
}
public void getServerList() {
new Thread(new Runnable() {
#Override
public void run() {
HttpURLConnection connection = null;
StringBuilder stringBuffer = new StringBuilder();
try {
URL url = new URL("my ip and blah balh");
connection = (HttpURLConnection) url.openConnection();
} catch (IOException e) {
e.printStackTrace();
}
if (connection != null) {
connection.setConnectTimeout(5000);
connection.setUseCaches(false);
try {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream(), "utf-8"));
String line = bufferedReader.readLine();
if (!"".equals(line)) {
stringBuffer.append(line);
Log.i("ServerListManager", stringBuffer.toString());
}
setServerListItem(stringBuffer.toString());
} catch (IOException e) {
e.printStackTrace();
}
}
}
}).start();
}
private void setServerListItem(String dataFromServer) {
Log.i("ServerListManager", "setServerListItem() works ");
ArrayList<ServerListItem> serverListItems = new ArrayList<>();
JsonParser jsonParser = new JsonParser();
JsonObject jsonObjectFirst = (JsonObject) jsonParser.parse(dataFromServer);
if (!String.valueOf(jsonObjectFirst.get("status")).equals("\"200\"")) {
Message message = new Message();
message.what = SERVER_PROBLEM;
handler.sendMessage(message);
} else {
String serverListJsonVersion = String.valueOf(jsonObjectFirst.get("serverModelList"));
JsonArray jsonArray = (JsonArray) jsonParser.parse(serverListJsonVersion);
Gson gson = new Gson();
for (JsonElement jsonElement : jsonArray) {
ServerListItem serverListItem = gson.fromJson(jsonElement, ServerListItem.class);
serverListItems.add(serverListItem);
}
ServerListActivity.serverListItemArrayList = serverListItems;
}
}

You can try using AsyncTask
private class AsyncCaller extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
//this method will be running on UI thread
//can call progress bar here to show loading process
}
#Override
protected Void doInBackground(Void... params) {
//this method will be running on background thread
//so don't update UI from here
//do your long running http tasks here,
//you don't want to pass argument and you
//can access the parent class' variable url over here
// call your server data here
serverListManager.getServerList();
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
//this method will be running on UI thread
//Show the result obtained from doInBackground
//this executed after doInBackground so after you get data from doInBackground
//you can set your adapter here
}
}
Then you can execute AsyncTask like this
new AsyncCaller().execute();

Unable to access string from class

I want to show string from another string in my MainActivity, but the string is getting printed in console. Here is my code:
public class MainActivity extends AppCompatActivity {
Button start;
public TextView showText;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
showText= (TextView)findViewById(R.id.textView);
start = (Button)findViewById(R.id.button);
start.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
RetrieveFeedTask click1 = new RetrieveFeedTask();
click1.execute();
showText.setText(click1.getString());
}
});
}
}
And the class:
class RetrieveFeedTask extends AsyncTask<Void, Void, String> {
static final String API_URL = "http://numbersapi.com/random/trivia?json";
private Exception exception;
public String finalString;
protected void onPreExecute() { }
protected String doInBackground(Void... urls) {
try {
URL url = new URL(API_URL );
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder stringBuilder = new StringBuilder();
while ((finalString = bufferedReader.readLine()) != null) {
stringBuilder.append(finalString).append("\n");
}
bufferedReader.close();
return stringBuilder.toString();
}
finally{
urlConnection.disconnect();
}
}
catch(Exception e) {
Log.e("ERROR", e.getMessage(), e);
return null;
}
}
protected void onPostExecute(String response) {
if(response == null) {
response = "THERE WAS AN ERROR";
}
try {
JSONObject object = (JSONObject) new JSONTokener(response).nextValue();
finalString = object.getString("text");
Log.i("Here",finalString);
} catch (JSONException e) {
}
}
public String getString() {
return this.finalString;
}
}

You require the finalString before it's populated with your data. the onPostExecute is executed after the doInBackground so you should pass your text view to your task and set it's value in the onPostExecute
public TextView showText;
public RetrieveFeedTask(TextView showText) { this.showText = showText; }
protected void onPostExecute(String response) {
if(response == null) {
response = "THERE WAS AN ERROR";
}
try {
JSONObject object = (JSONObject) new JSONTokener(response).nextValue();
finalString = object.getString("text");
showText.setText(finalString ); // add this
Log.i("Here",finalString);
} catch (JSONException e) {
}
}

The problem is that showText.setText(click1.getString()); of your activity is called earlier than finalString = object.getString("text"); of your task.
Solution:
Create an interface:
public interface DataCallback {
void onNewData(String data);
}
and implement it in your activity:
public class MainActivity extends ... implements DataCallback
public void onNewData(String data) {
showText.setText(data);
}
Pass the interface to your asynctask when you create it:
RetrieveFeedTask click1 = new RetrieveFeedTask(this);
Call the interface inside the task in onPostExecute() to notify the activity that there is new data:
JSONObject object = (JSONObject) new JSONTokener(response).nextValue();
finalString = object.getString("text");
callback.onNewData(finalString);

Android passing a string to a php file

Here is my java android code which should pass 'Preferred hotels' string to a php file and later read what have been passed.
sendSubMenuDetail("Preferred hotels");
This is evoked at the activity load. Whose function is below:
public void sendSubMenuDetail(String suggestion){
String urlSuffix = "?suggestion="+suggestion;
class RegisterUser extends AsyncTask<String, Void, String> {
ProgressDialog loading;
#Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(ActivitySubMenu.this, "Please Wait",null, true, true);
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
loading.dismiss();
Toast.makeText(getBaseContext(),s,Toast.LENGTH_LONG).show();
}
#Override
protected String doInBackground(String... params) {
String s = params[0];
BufferedReader bufferedReader = null;
try {
URL url = new URL(address+s);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String result;
result = bufferedReader.readLine();
return result;
}catch(Exception e){
return null;
}
}
}
RegisterUser ru = new RegisterUser();
ru.execute(urlSuffix);
}
The output dislayed in a toast here is 'Preferred' instead of 'Preferred hotels'. I tried figuring out what the problem might be with no success.

Pass-parameter when calling a function in Java

in java, i'm calling a function which reads a text file's content from the web into a variable, but my problem is that the file's url is hardcoded in the functio. I would like to use this function several times for different files. So how can i manage, to add the file's url when i call the function?
The function is;
public class readtextfile extends AsyncTask<String, Integer, String>{
private TextView description;
public readtextfile(TextView descriptiontext){
this.description = descriptiontext;
}
#Override
protected String doInBackground(String... params) {
URL url = null;
String result ="";
try {
url = new URL("http://example.com/description1.txt");
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
String line = null;
while ((line = in.readLine()) != null) {
result+=line;
}
in.close();
}
catch (MalformedURLException e) {e.printStackTrace();}
catch (IOException e) {e.printStackTrace();}
return result;
}
protected void onProgressUpdate() {
//called when the background task makes any progress
}
protected void onPreExecute() {
//called before doInBackground() is started
}
#Override
protected void onPostExecute(String result) {
this.description.setText(result);
}
}
Where i'm calling the function:
public class PhotosActivity extends Activity {
TextView description;
String descriptiontext;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.photos_layout);
description = ((TextView)findViewById(R.id.description1));
new readtextfile(description).execute();
}
}

Using AsyncTask for a single task is not a good solution, you should better look to Threads.
But if you want to use AsyncTask, anyway, you can add a constructor like this :
public readtextfile(TextView descriptiontext, String url){
this.description = descriptiontext;
this.url = url;
}
And use this.url in your doInBackground.