如何将 Class 中的值放入我的 TextViewField

Question

At the moment I am trying to make an Android App with Android Studio with GET and POST data into/from an API.

My problem at the moment is that I want to have the response of the POST request displayed in my app. For this I made the TextView TW_Rueckgabe. I also made another Method just for this so it can Display the Request which is

public String returnString() {
        return fetching_data;
    }

but the response is not saved in TW_Rueckgabe.

MainActivity.java

final TextView[] TW_Rueckgabe = {findViewById(R.id.textViewRueckgabe)};

Button sendBtn = findViewById(R.id.sendBtn);

        sendBtn.setOnClickListener(v -> {
            String POST_url = "http://dphost.ddns.net:1573/cool/post.php";
            String requestData = "data=" + TW_Benutzername.getText().toString();
            POSTRequestTask test = (POSTRequestTask) new POSTRequestTask().execute(POST_url, requestData);

            

            TW_Rueckgabe[0].setText(test.fetching_data);

        });

POSTRequestTask Class:

class POSTRequestTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... params) {
        String url = params[0];
        String requestData = params[1];
        String response = "";

        try {
            URL obj = new URL(url);
            HttpURLConnection con = (HttpURLConnection) obj.openConnection();

            // add request header
            con.setRequestMethod("POST");
            con.setDoOutput(true);

            // add request data
            DataOutputStream wr = new DataOutputStream(con.getOutputStream());
            wr.writeBytes(requestData);
            wr.flush();
            wr.close();

            int responseCode = con.getResponseCode();
            System.out.println("\nSending 'POST' request to URL : " + url);
            System.out.println("Response Code : " + responseCode);

            BufferedReader in = new BufferedReader(
                    new InputStreamReader(con.getInputStream()));
            String inputLine;
            StringBuffer responseBuffer = new StringBuffer();

            while ((inputLine = in.readLine()) != null) {
                responseBuffer.append(inputLine);
            }
            in.close();

            response = responseBuffer.toString();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return response;
    }

    @Override
    protected void onPostExecute(String result) {
        // print result
        System.out.println("\n\n\n" + result + "\n\n\n");
        fetching_data = result;
        
    }

public String returnString() {
        return fetching_data;
    }
}

I tried to make a new Object and then save the Variable from the Object, didn't work.

Answer 1

interface Callback {
   void onResponse(String response);
}

MainActivity {

   private Callback callback = new Callback() {
       @Override
       void onResponse(String response) {
            TW_Rueckgabe[0].setText(test.fetching_data);
       }
   }

    sendBtn.setOnClickListener(v -> {
            String POST_url = "http://dphost.ddns.net:1573/cool/post.php";
            String requestData = "data=" + TW_Benutzername.getText().toString();
            POSTRequestTask test = new POSTRequestTask(callback).execute(POST_url, requestData);
        });
}


class POSTRequestTask(Callback callback) extends AsyncTask<String, Void, String> {

@Override
    protected String doInBackground(String... params) {
       // do your request as you're doing now and return the result
    }

    @Override
    protected void onPostExecute(String result) {
        // callback interface method call here
        callback.onResponse(result)
    }
}