Question

I have just finished a Java test at university and I know that I have answered a particular question wrong and would just like some help / clarification please?

The question was as follows:

implement a method that takes someones income and works out the tax.
If that person earns less than 7500 then tax = 0.
If that person earns between 7501 and 45000 then tax = 20%, less the 7500, which is tax free.
Finally, if that person earns above 45001 then tax = 40%, less the income in the 20% bracket, and then less the 7500 which is tax free.

As time was running short, I just did a basic if else statement showing income and tax brackets, example below.

public static double incomeTax(double income){

    if(income <= 7500){
           income = income * 0;
       }
     else if(income >= 7501 && income <= 45000){
           income = income * 0.8;
       }
     else(income >= 45001){
           income = income * 0.6;
       }
     return income;
} 

I know that the code is not correct, no where near, but as it was coming to the end of the test I gave it a go in a hope just to get a mark for the if else statements.

I would really appreciate any help here.

Thank you.

After great feedback, this is what I came back with (with a LOT of help!!:] )…

import java.util.Scanner;

public class TaxableIncome
{
public static void main(String[] args){
    netIncome();
}

public static double netIncome() {
    double income = 0;

    Scanner in = new Scanner(System.in);

    System.out.print("Enter income: ");
    income = in.nextDouble();
    System.out.println();

    double tax1 = 0;
    double tax2 = 0;
    double totalTax = tax1 + tax2;

    // high income bracket
    if (income > 45000) {
        double part1 = income - 45000; // part = income - 45000
        tax1 += part1 * 0.4; // tax = tax + part * 0.4
        System.out.println("High Tax Band - Greater than 45000: " + tax1);
    }

    // medium income bracket
    if (income >  7500) {
        double part2 = income - 7500;
        tax2 += part2 * 0.2;
        System.out.println("Medium Tax Band - Greater than 7500: " + tax2);
    }

    System.out.println("Total Tax = " + (tax1 + tax2));

    // tax for low income is zero, we don't need to compute anything.

    return totalTax;
   }
}

Answer 1

A simple answer would be as this:

public static double netIncome(double income) {

  double tax = 0;

  // high income bracket
  if (income > 45000) {
    double part = income - 45000;
    tax += part * 0.4;
    income = 45000;
  }

  // medium income bracket
  if (income >  7500) {
    double part = income - 7500;
    tax += part * 0.2;
  }

  // tax for low income is zero, we don't need to compute anything.

  return tax;
}

This way you calculate the tax for each tax bracket and sum them.