java - Define text color based on value using AsyncTask

Question

So basically my AsyncTask get the value from the url and when i execute i wanna show green text or red text if contains ("-"). I have search around and none of the option worked for me. i do have a RecyclerView.ViewHolder but don't know how to incorporate before i execute. Everything works, except the colors. Thank you in advance

Activity

public class BTCData extends AsyncTask<Void,RecyclerView.ViewHolder,Void> {
    String data = "";
    String dataParsed1h ="";
    String dataParsed24h ="";
    String dataParsed7d ="";
    String percent_change_1h = "";
    String percent_change_24h = "";
    String percent_change_7d = "";
    Activity activity;
    List<Model> items;

    public BTCData() {

    }

    @Override
    protected Void doInBackground(Void... voids) {
        try {
            URL url = new URL ("https://...");
            HttpURLConnection httpURLConnection = (java.net.HttpURLConnection) url.openConnection();
            InputStream inputStream = httpURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            String line = "";
            while (line != null){
                line = bufferedReader.readLine();
                data = data+line;
            }

            JSONArray JA = new JSONArray(data);
            for(int i=0 ;i< JA.length(); i++){
                JSONObject JO = (JSONObject) JA.get(i);
                percent_change_1h =  "1H  " + JO.getString("percent_change_1h") + "%";
                percent_change_24h = "24H  " + JO.getString("percent_change_24h") + "%";
                percent_change_7d = "7D  " + JO.getString("percent_change_7d") + "%" ;

                dataParsed1h = dataParsed1h + percent_change_1h;
                dataParsed24h = dataParsed24h + percent_change_7d;
                dataParsed7d = dataParsed7d + percent_change_24h;


            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        MainActivity.btc_percent_change_1h.setText(this.dataParsed1h);
        MainActivity.btc_percent_change_24h.setText(this.dataParsed24h);
        MainActivity.btc_percent_change_7d.setText(this.dataParsed7d);
    }
}```

**View Holder**

public class CoinAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

Adapter adapter;
boolean isLoading;
Activity activity;
List<Model> items;

int visibleThreshold = 5,lastVisibleItem, totalItemcount;

public void setAdapter(Adapter adapter) {
    this.adapter = adapter;
}

@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(activity)
            .inflate(R.layout.activity_main,parent,false);
    return new CoinViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
    Model item = items.get(position);
    CoinViewHolder holderItem = (CoinViewHolder)holder;

    holderItem.btc_percent_change_1h.setTextColor(item.getPercentage_change_1h().contains("-")?
            Color.parseColor("#FF0000"):Color.parseColor("#32CD32"));
    holderItem.btc_percent_change_24h.setTextColor(item.getPercentage_change_24h().contains("-")?
            Color.parseColor("#FF0000"):Color.parseColor("#32CD32"));
    holderItem.btc_percent_change_7d.setTextColor(item.getPercentage_change_7d().contains("-")?
            Color.parseColor("#FF0000"):Color.parseColor("#32CD32"));

}

@Override
public int getItemCount() {
    return items.size();
}
public void setLoader() {isLoading = true;}
public void updateData (List<Model> models)
{
    this.items = models;
    notifyDataSetChanged();
}

**on Activity**


    public static TextView btc_percent_change_1h;
    public static TextView btc_percent_change_24h;
    public static TextView btc_percent_change_7d;



//Percentage
        btc_percent_change_1h = (TextView) findViewById(R.id.btc_percent_change_1h);
        btc_percent_change_24h = (TextView) findViewById(R.id.btc_percent_change_24h);
        btc_percent_change_7d = (TextView) findViewById(R.id.btc_percent_change_7d);


and finally call...

BTCData process = new BTCData();
        process.execute();

question from:https://stackoverflow.com/questions/65897417/define-text-color-based-on-value-using-asynctask

Answer 1

This is because for setting color you are doing in onBindViewHolder when in that case data would be 0 only without red sign and later you are setting data but after that onBindViewHolder is not called and hence changes are not reflecting.

The way you are doing all this is not ideal way and would suggest you to read design patterns to implement it in proper way.