Reuse Drawable java file for Android article on medium.com

MainActivity.java

package com.asadchattha.reusedrawable;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.content.ContextCompat;

import android.graphics.drawable.GradientDrawable;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    /**
     * Handle click events for button(Change Color)
     */
    public void onClickButton(View view) {
        // Return random number between 1 to 3
        int randomNumber = new Random().nextInt(3)+1;
        updateDisplay(randomNumber);
    }

    /**
     * Update TextView background color (according to given input)
     * by changing color of {@link circle.xml} drawable
     */
    private void updateDisplay(int number){
        // Find the TextView with view ID number_textView
        TextView numberTextView = findViewById(R.id.number_textView);
        // Display the current random number in TextView
        numberTextView.setText(String.valueOf(number));

        // Set the proper background color on the number circle.
        // Fetch the background from the TextView, which is a GradientDrawable.
        GradientDrawable numberCircle = (GradientDrawable) numberTextView.getBackground();
        // Get the appropriate background color based on the current number
        int numberColor = getNumberColor(number);
        // Set the color on the magnitude circle
        numberCircle.setColor(numberColor);
    }

    /**
     * Return the color for the number circle based on the input number.
     *
     * @param randomly generated number
     */
    private int getNumberColor(int number) {
        int numberColorResourceId;
        int magnitudeFloor = (int) Math.floor(number);
        switch (magnitudeFloor) {
            case 0:
            case 1:
                numberColorResourceId = R.color.number1;
                break;
            case 2:
                numberColorResourceId = R.color.number2;
                break;
            case 3:
                numberColorResourceId = R.color.number3;
                break;
            default:
                numberColorResourceId = R.color.number_default;
                break;
        }

        return ContextCompat.getColor(MainActivity.this, numberColorResourceId);
    }
}