First up, I am totally new to android and java so, a very steep learning curve for me, been at it a few days now looking at all sorts of answers both here and other places lots of tries but still no solution.

Edit: Just to be clear, I have spent at least a couple of days attempting to find the answer (researching), lots of "answers" out there if you have at least some experience in android and java.

Using Android Studio...

What I am attempting to do is set the TextView to the returned value from a Socket call, input = new BufferedReader(new InputStreamReader(socket.getInputStream()));

This call returns a value that is a correct response from a hardware device, so the socket works fine (remember, this is a learning curve so I don't need to know what I may be doing wrong, that will come later) all I want at this point in time is to set the text view with the returned value of the BufferedRead input var.

This --> TextView te = (TextView)findViewById(R.id.textView); shows as a problem "Cannot resolve method 'findViewById' in 'FirstFragment'" even though the TextView is actually in the fragment and also shows in the associated xml file.

Sorry if I have not explained this well but, I am trying.

Any advice would be helpful

package com.example.mybasicactivityapp;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.navigation.fragment.NavHostFragment;

import com.example.mybasicactivityapp.databinding.FragmentFirstBinding;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.nio.CharBuffer;

public class FirstFragment extends Fragment {
    private FragmentFirstBinding binding;

    TextView te;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState)
        {

    TextView te = (TextView)findViewById(R.id.textView);

    String RequestA = "/?00044000039400!\r\n";
    
            Runnable runnable = new Runnable(){
                @Override
                public void run() {
                    try {
                        Socket socket = new Socket(ipAddress, port);
                        OutputStream out = socket.getOutputStream();
                        PrintWriter output = new PrintWriter(out, true);
                        output.println(RequestA);
                        BufferedReader input;
                        input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                        String read = input.readLine();
                        String t = read;
                        
                        te = findViewById(R.id.textView);

                    }
                    catch (IOException e)
                    {
                        e.printStackTrace();
                    }
                }
            };
            Thread thread = new Thread(runnable);
            thread.start();

        binding = FragmentFirstBinding.inflate(inflater, container, false);


        return binding.getRoot();

    }

    public void onViewCreated(@NonNull View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        binding.buttonFirst.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                NavHostFragment.findNavController(FirstFragment.this)
                        .navigate(R.id.action_FirstFragment_to_SecondFragment);
            }
        });
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        binding = null;
    }

}

CodePudding user response：

You have to call getView() before findViewById.

Such as

TextView te = (TextView)getView().findViewById(R.id.textView);

Note that getView() only works after onCreateView finishes, so you will also need to move this to the onViewCreated method.

CodePudding user response：

You have to get the reference to the textView from inside the onViewCreated method. Do something like binding.textView in onViewCreated method to access the textView.

CodePudding user response：

You do too much unnecessary findViewById and declare TextView

just use binding.textView to get TextView

public class FirstFragment extends Fragment {
    private FragmentFirstBinding binding;

    TextView te; //unnecessary

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState)
        {

    TextView te = (TextView)findViewById(R.id.textView);//unnecessary

    String RequestA = "/?00044000039400!\r\n";
    
            Runnable runnable = new Runnable(){
                @Override
                public void run() {
                    try {
                       ...
       
                        String t = read;
                        
                        te = findViewById(R.id.textView);//unnecessary
                        binding.textView.text = t //add this line
                    }
                    catch (IOException e)
                    {
                        e.printStackTrace();
                    }
                }
            };
            Thread thread = new Thread(runnable);
            thread.start();

        binding = FragmentFirstBinding.inflate(inflater, container, false);


        return binding.getRoot();

    }
}