Dynamic TextSwitcher in Android

package com.gtappdevelopers.kotlingfgproject;

import android.graphics.Color;
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.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextSwitcher;
import android.widget.TextView;
import android.widget.ViewSwitcher;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    // on below line we are creating variables.
    private LinearLayout containerLL;
    String languages[] = {"Java", "C", "Kotlin", "C++"};
    int index = 0;

    @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);

        // 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 our dynamic text view
        TextView headingTV = new TextView(this);

        // on below line we are setting  for our text view.
        headingTV.setText("Dynamic Text Switcher 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);

        // on below line we are creating a simple text switcher.
        TextSwitcher textSwitcher = new TextSwitcher(this);

        // on below line we are setting factor for our text switcher.
        textSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
            @Override
            public View makeView() {
                // on below line we are adding a text view in our text switcher.
                TextView textView = new TextView(MainActivity.this);
                
                // on below line we are adding gravity for our text
                textView.setGravity(Gravity.CENTER_HORIZONTAL);
                
                // on below line we are adding a text size
                textView.setTextSize(32f);
                
                // on below line we are adding a padding,
                textView.setPadding(100, 100, 100, 100);
                
                // on below line we are setting color for our text
                textView.setTextColor(Color.BLACK);
                return textView;
            }
        });

        // on below line we are setting text for text switcher.
        textSwitcher.setText(languages[index]);

        // on below line we are creating a variable 
        // for our slide-in animation
        Animation textIn = AnimationUtils.loadAnimation(
                this, android.R.anim.slide_in_left
        );
        
        // on below line we are setting animation 
        // to our text switcher.
        textSwitcher.setInAnimation(textIn);

        // on below line we are creating a variable
        // for slide out animation
        Animation textOut = AnimationUtils.loadAnimation(
                this, android.R.anim.slide_out_right
        );
        
        // on below line we are setting out 
        // animation for text switcher
        textSwitcher.setOutAnimation(textOut);

        // on below line we are creating a layout params for button
        LinearLayout.LayoutParams buttonParam = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT
        );
        
        // on below line we are adding margin for buttons.
        buttonParam.setMargins(10, 10, 10, 10)

        // on below line we are creating a previous button
        // and adding text and style to it on below line
        Button prevBtn = new Button(this);
        prevBtn.setText("Previous");
        prevBtn.setAllCaps(false);
        
        // on below line setting params to it.
        prevBtn.setLayoutParams(buttonParam);
        
        // on below line we are setting text color to it.
        prevBtn.setTextColor(getResources().getColor(R.color.white));
        
        // on below line we are adding background color to it.
        prevBtn.setBackgroundColor(getResources().getColor(R.color.purple_200));
        
        // on below line we are adding click listener
        prevBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // on below line we are updating index
                if (index - 1 >= 0) {
                    index = index - 1;
                } else {
                    index = 3;
                }
                textSwitcher.setText(languages[index]);
            }
        });

        // on below line we are creating a next button
        // and adding text and style to it on below line
        Button nextBtn = new Button(this);
        nextBtn.setText("Next");
        nextBtn.setAllCaps(false);
        
        // on below line setting params to it.
        nextBtn.setLayoutParams(buttonParam);
        
        // on below line we are setting text color to it.
        nextBtn.setTextColor(getResources().getColor(R.color.white));
        
        // on below line we are adding background color to it.
        nextBtn.setBackgroundColor(getResources().getColor(R.color.purple_200));
        
        // on below line we are adding click listener
        nextBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // on below line we are updating index
                if (index + 1 < languages.length) {
                    index = index + 1;
                } else {
                    index = 0;
                }
                textSwitcher.setText(languages[index]);
            }
        });

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

    }
}