从OkHttp获取字符串并将该字符串导入另一个类

long story quick , im IT guy , i have learned basic of Python and now i want to learn java but currently im doing a project in android studio without much knowledge so i dont have time to learn java for the moment , well im in a situation that is making me crazy.Project is IPTV player, im trying to get string with OkHttp3 and attach it to end of IPTV link to make it playable , i try GET with Postman and i get the result , i create new project in android studio and try OkHttp3 for first time (i saw youtube video), and i can succesfuly get the respond i want from OkHttp3 but the respond i get into textview, now in my main project for iptv i want to store the response into String i think and attach to the end of the IPTV link , i try to store response into textview but app crashes, i belive the good way is to store into String , so far down public class i done : TextView mCodeFromUrl; my OkHttp3 code below onCreate is :

        mCodeFromUrl = findViewById(R.id.test1);

    OkHttpClient client = new OkHttpClient();
    String url = "http://192.168.100.6/1.php";
    Request request = new Request.Builder()
            .url(url)
            .build();
    client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(@NonNull Call call, @NonNull IOException e) {
            e.printStackTrace();
        }

        @Override
        public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
            if (response.isSuccessful()){
                assert response.body() != null;
                String myResponse = response.body().string();

                TVDetailsActivity.this.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        mCodeFromUrl.setText(myResponse);


                    }
                });
            }
        }
    });

this works for new project with textview , but in main project i get crash , is there any possibility to get string and store into another class or i dont know , im so out of ideas , i also tried to create string below public class : String Test1 = "testurl"; then into OkHttp3 code it try to give my string Test1 the response like this : Test1 = Test1 + myResponse; Down below into the code i try to add : + Test1 code: ExoPlayerFragment exoPlayerFragment = ExoPlayerFragment.newInstance(itemChannel.getChannelUrl() + Test1); fragmentManager.beginTransaction().replace(R.id.playerSection, exoPlayerFragment).commitAllowingStateLoss();

then the app load perfect but when im about to get the response and place it behind the IPTV link i get the string and not the response like this ...lista.m3u8testurl Help me please and if possibility any recommended youtube channel to learn java, Thanks a lot

更新：是否可以创建新类并将所有OkHttp3代码放入其中，然后在需要的地方使用代码执行？因为当客户端单击频道以观看电视时，并且在后台执行OkHttp3，并且响应在IPTV链接后面，然后客户端可以播放IPTV时，我想获得响应。