LESSON 162 OF 410 · PROJECTS: EVERYDAY PROGRAMS

Shopping Cart V5 - Coupon Codes in Java

Practice

Use a map as a fast lookup table for coupon discounts.

You start with:

int subtotal = 100;
String coupon = "SAVE20";
HashMap<String, Integer> coupons = new HashMap<>();
coupons.put("SAVE10", 10);
coupons.put("SAVE20", 20);
coupons.put("SAVE50", 50);

Build:

Total: $80

Rules:

Look up coupon in coupons. If it is there, its value is the discount; if it is not (an unknown code), the discount is 0.
total = subtotal - discount.
Build the text "Total: $<total>" (e.g. "Total: $80"; an unknown coupon would give "Total: $100").
Store it in result, then print it with System.out.println(result).

Use coupons.getOrDefault(coupon, 0): it returns the value if the key is present, or 0 if it is missing.

In Java "Total: $" + total converts the number to text for you.

int subtotal = 100;
String coupon = "SAVE20";
HashMap<String, Integer> coupons = new HashMap<>();
coupons.put("SAVE10", 10);
coupons.put("SAVE20", 20);
coupons.put("SAVE50", 50);

int discount = coupons.getOrDefault(coupon, 0);
int total = subtotal - discount;
String result = "Total: $" + total;
System.out.println(result);

STEP 1 OF 4

Guided

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Shopping Cart V5 - Coupon Codes in Java

Shopping Cart V5 in Java