Exercise08_12.java

package ch_08;

import java.util.*;

/**
 * 8.12 (Financial application: compute tax) Rewrite Listing 3.5, ComputeTax.java,
 * using arrays. For each filing status, there are six tax rates. Each rate is applied
 * to a certain amount of taxable income.
 * <p>
 * For example, from the taxable income of $400,000 for a single filer, $8,350 is taxed at 10%, (33,950 - 8,350) at 15%,
 * (82,250 - 33,950) at 25%, (171,550 - 82,550) at 28%, (372,550 - 82,250) at
 * 33%, and (400,000 - 372,950) at 36%. The six rates are the same for all filing
 * statuses, which can be represented in the following array: double[] rates = {0.10, 0.15, 0.25, 0.28, 0.33, 0.35};
 * The brackets for each rate for all the filing statuses can be represented in a two-dimensional array as follows:
 * int[][] brackets = { {8350, 33950, 82250, 171550, 372950}, // Single filer
 * {16700, 67900, 137050, 20885, 372950}, // Married jointly -or qualifying widow(er)
 * {8350, 33950, 68525, 104425, 186475}, // Married separately
 * {11950, 45500, 117450, 190200, 372950} // Head of household
 * };
 * Suppose the taxable income is $400,000 for single filers. The tax can be computed as follows:
 * tax = brackets[0][0] * rates[0] +
 * (brackets[0][1] – brackets[0][0]) * rates[1] +
 * (brackets[0][2] – brackets[0][1]) * rates[2] +
 * (brackets[0][3] – brackets[0][2]) * rates[3] +
 * (brackets[0][4] – brackets[0][3]) * rates[4] +
 * (400000 – brackets[0][4]) * rates[5]
 */
public class Exercise08_12 {
    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);

        double[] rates = {0.10, 0.15, 0.25, 0.28, 0.33, 0.35};
        int[][] brackets = {
                {8350, 33950, 82250, 171550, 372950}, // Single filer
                {16700, 67900, 137050, 20885, 372950}, // Married jointly  -or qualifying widow(er)
                {8350, 33950, 68525, 104425, 186475}, // Married separately
                {11950, 45500, 117450, 190200, 372950} // Head of household
        };

        System.out.print("\n(0-single filer, 1-married jointly or "
                + "qualifying widow(er), 2-married separately, 3-head of " + "household) Enter the filing status: ");
        int status = input.nextInt();
        if (status > 3) {
            System.out.println("Error, Invalid Filling Status");
            return;
        }

        // Prompt the user to enter taxable income
        System.out.print("\nEnter the taxable income: ");
        double income = input.nextDouble();


        System.out.printf("Tax is $%.2f", calcTax(income, brackets[status], rates));
        input.close();

    }

    /**
     * * tax = brackets[0][0] * rates[0] +
     * * (brackets[0][1] – brackets[0][0]) * rates[1] +
     * * (brackets[0][2] – brackets[0][1]) * rates[2] +
     * * (brackets[0][3] – brackets[0][2]) * rates[3] +
     * * (brackets[0][4] – brackets[0][3]) * rates[4] +
     * * (400000 – brackets[0][4]) * rates[5]
     *
     * @param income  taxableIncome
     * @param bracket the tax bracket
     * @param rates   array of rate tiers
     * @return amount of tax: double
     */
    static double calcTax(double income, int[] bracket, double[] rates) {
        double tax = 0;
        if (income <= bracket[0]) {
            tax = income * rates[0];
        } else if (income <= bracket[1]) {
            tax = bracket[0] * rates[0] + (income - bracket[0]) * rates[1];
        } else if (income <= bracket[2]) {
            tax = bracket[0] * rates[0] + (bracket[1] - bracket[0]) * rates[1] + (income - bracket[1]) * rates[2];
        } else if (income <= bracket[3]) {
            tax = bracket[0] * rates[0] + (bracket[1] - bracket[0]) * rates[1] + (bracket[2] - bracket[1]) * rates[2]
                    + (income - bracket[2]) * rates[3];
        } else if (income <= bracket[4]) {
            tax = bracket[0] * rates[0] + (bracket[1] - bracket[0]) * rates[1] + (bracket[2] - bracket[1]) * rates[2]
                    + (bracket[3] - bracket[2]) * rates[3] + (income - bracket[4]) * rates[4];
        } else
            tax = bracket[0] * rates[0] + (bracket[1] - bracket[0]) * rates[1] + (bracket[2] - bracket[1]) * rates[2]
                    + (bracket[3] - bracket[2]) * rates[3] + (bracket[4] - bracket[3]) * rates[4] + (income - bracket[4]) * rates[5];

        return tax;

    }
}