Calling private methods from inside the constructor in Java

I have the following class:

package com.tesco.demandforecasting.group8.choprachap7;

import java.util.ArrayList;

import com.tesco.demandforecasting.group8.utils.MathOperUtils;
import com.tesco.demandforecasting.group8.utils.RegressionUtils;

import lombok.Getter;

/**
 * This class if used to find seasonality factor of each period, as explain in
 * the chapter See https://kelley.iu.edu/mabert/e730/Chopra-Chap-7.pdf for the
 * explanation
 */
@Getter
public class ChopraChap7SeasonalFactorsCalculator {

    private double[] regressionParams;

    private int sales_size;
    private int periodicity;

    private ArrayList<Integer> sales;
    private ArrayList<Double> deseasonalisedData;
    private ArrayList<Double> deseasonalisedDemandUsingRegression;
    private ArrayList<Double> seasonalityFactors;

    public ChopraChap7SeasonalFactorsCalculator() {

        this.sales = new ArrayList<>();
        this.deseasonalisedData = new ArrayList<>();
        this.deseasonalisedDemandUsingRegression = new ArrayList<>();
        this.seasonalityFactors = new ArrayList<>();

        this.sales.add(8000);
        this.sales.add(13000);
        this.sales.add(23000);
        this.sales.add(34000);
        this.sales.add(10000);
        this.sales.add(18000);
        this.sales.add(23000);
        this.sales.add(38000);
        this.sales.add(12000);
        this.sales.add(13000);
        this.sales.add(32000);
        this.sales.add(41000);

        this.sales_size = sales.size();
        this.periodicity = 4;

        calculateSeasonalityFactors();
    }


    private void calculateSeasonalityFactors() {

        .......
        .......

        this.seasonalityFactors = seasonalityFactors;
        this.deseasonalisedDemandUsingRegression = deseasonalisedDemandUsingRegression;
        this.deseasonalisedData = deseasonalisedData;

    }

}

I want to expose the class fields to external classes, using their respective getters. But, the problem is that those fields attain any value only after the ChopraChap7SeasonalFactorsCalculator() method is called. So, what I have done here is call the method as soon as an object of the class is created. Of course, this will work, but is this good design pattern?

Supposing I would not have called the method from the constructor. So, if we have the following code is some other class:

ChopraChap7SeasonalFactorsCalculator calc = new ChopraChap7SeasonalFactorsCalculator();
calc.getDeseasonalisedData();

This will return to me any empty array list. How do I ensure that the method is called before any field is accessed?

What would be the best design pattern in my case?