Dynamic Spinner in Android

package com.gtappdevelopers.kotlingfgproject;

import android.graphics.Typeface;
import android.os.Build;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    // on below line we are creating variables.
    private LinearLayout containerLL;
    private ArrayList<String> languageList;

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR1)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // on below line we are initializing our variables.
        containerLL = findViewById(R.id.idLLContainer);
        languageList = new ArrayList<>();

        // on below line we are adding 
        // languages to our language list
        languageList.add("Java");
        languageList.add("Kotlin");
        languageList.add("C++");
        languageList.add("C");

        // on below line we are creating layout params for text view.
        // and specifying width as match parent and height as wrap content
        LinearLayout.LayoutParams txtLayoutParam = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT
        );
        // on below line we are adding gravity
        txtLayoutParam.gravity = Gravity.CENTER;

        // on below line we are creating layout params for spinner.
        // and specifying width as wrap parent and height as wrap content
        LinearLayout.LayoutParams spinnerLayoutParam = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT
        );
        // on below line we are adding gravity
        spinnerLayoutParam.gravity = Gravity.CENTER;

        // on below line we are creating our dynamic text view
        TextView headingTV = new TextView(this);
       
        // on below line we are setting  for our text view.
        headingTV.setText("Dynamic Spinner in Android");
        
        // on below line we are updating text size.
        headingTV.setTextSize(20f);
        
        // on below line we are updating text color and font
        headingTV.setTextColor(getResources().getColor(R.color.black));
        headingTV.setTypeface(Typeface.DEFAULT_BOLD);
        
        // on below line we are adding padding
        headingTV.setPadding(20, 20, 20, 20);
        
        // on below line we are specifying text alignment.
        headingTV.setTextAlignment(View.TEXT_ALIGNMENT_CENTER);
        
        // on below line we are adding layout param 
        // for heading text view.
        headingTV.setLayoutParams(txtLayoutParam);

        // create spinner programmatically
        Spinner spinner = new Spinner(this);
        
        // on below line we are adding params for spinner.
        spinner.setLayoutParams(spinnerLayoutParam);

        // on below line we are adding our 
        // views to container linear layout
        containerLL.addView(headingTV);
        containerLL.addView(spinner);

        // on below line we are checking if spinner is not null
        if (spinner != null) {
            // on below line we are initializing and setting our adapter
            // to our spinner.
            ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_spinner_item, languageList);
            spinner.setAdapter(adapter);
            // on below line we are adding on item selected listener for spinner.
            spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                    // in on selected listener we are displaying a toast message
                    Toast.makeText(MainActivity.this, "Selected Language is : " + languageList.get(position), Toast.LENGTH_SHORT).show();
                }

                @Override
                public void onNothingSelected(AdapterView<?> parent) {

                }
            });
        }
    }
}