Tool Setup

Test/TaxApp.java

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+package Test;
+abstract class TaxCalculator {
+    protected double income;
+
+    public TaxCalculator(double income) {
+        this.income = income;
+    }
+    public abstract double calculateTax();
+    public double afterTaxIncome() {
+        return income - calculateTax();
+    }
+}
+class FlatTaxCalculator extends TaxCalculator {
+    private static final double RATE = 0.15;
+    public FlatTaxCalculator(double income) {super(income);}
+    public double calculateTax() {
+        return income * RATE;
+    }
+}
+
+public class TaxApp {
+    static class BracketTaxCalculator extends TaxCalculator {
+        public BracketTaxCalculator(double income) {
+            super(income);
+        }
+        public double calculateTax() {
+            if (income <= 10000) {return income * 0.10;} 
+            else if (income <= 50000) { return (10000 * 0.10) + ((income - 10000) * 0.20);}
+            else { return (10000 * 0.10) + (40000 * 0.20) + ((income - 50000) * 0.30);}
+        }
+    }
+
+    public static void main(String[] args) {
+        double income = 60000;
+
+        TaxCalculator flat = new FlatTaxCalculator(income);
+        double flatTax = flat.calculateTax();
+        double flatAfterTax = flat.afterTaxIncome();
+
+        TaxCalculator bracket = new BracketTaxCalculator(income);
+        double bracketTax = bracket.calculateTax();
+        double bracketAfterTax = bracket.afterTaxIncome();
+    }
+}