How can you multiply a string with an integer in Java?

Question

I was just writing code for project that's due for class but I'm having a problem because I need to multiply my string with a number. Here's parts of my code

int shoes=50;
int shirts=30;
int shorts=75;
int caps=15;
int jackets=100;

Those above are the products and how much they cost in dollars:

    System.out.print("Enter the product: ");
String product=keyboard.nextLine();
System.out.print("Enter the quantity of the product");
int quantity=keyboard.nextInt();    
System.out.print("cost= +product+*+quantity+");
int cost= product*quantity;

This is the error I'm having: The operator * is undefined for the argument type(s) string, int

Any suggestions?

How on earth is `cost = product * quantity` a sensible equation? What are you reading into `product`? Is it `cost/product`? If yes, shouldn't that be declared as an `int` too? — Rohit Jain, Mar 07 '14 at 21:27
Your print should be `System.out.print("cost= " + product*quantity);` — Zach Saucier, Mar 07 '14 at 21:29
What do you mean with multiply a string by an integer. Can you give more explanation. — ديناصور الأمة, Mar 07 '14 at 21:30
Ok, I didn't notice that you've stored cost/product in variables. In that case, you certainly need a `Map`, else you can't get the product cost from string — Rohit Jain, Mar 07 '14 at 21:30
Let's say I want 3 caps. The string would be caps and the quanitity would be 3 — user3394363, Mar 07 '14 at 21:33
possible duplicate of [Get variable by name from a String](http://stackoverflow.com/questions/13298823/get-variable-by-name-from-a-string) — femtoRgon, Mar 07 '14 at 21:34

score 4 · Answer 1 · answered Mar 07 '14 at 21:29

4

You may want to use a Map to map each product with its cost.

Map<String, Integer> productMap = new HashMap<String, Integer>();
productMap.put("shoes",50);
...

And then just do:

int cost= productMap.get(product)*quantity;

answered Mar 07 '14 at 21:29

Alexis C.

91,686
21
171
177

score 2 · Answer 2 · answered Mar 07 '14 at 21:29

You need a way to look up a price given a product name. One way is using a Map:

Map<String,Integer> productPrices = new HashMap<String,Integer>();

This creates a container that will hold Integer values that can be looked up using a String.

Then add your products to it:

productPrices.put("shoes", 50);
productPrices.put("shirts", 30);

and so on. Then to calculate your cost:

Integer cost = productPrices.get(product) * quantity;

score 1 · Answer 3 · answered Mar 07 '14 at 21:27

1

You need to convert to and integer first:

int stringAsInt = 0;
try{
  stringAsInt  = Integer.parseInt(yourStringHere);
}catch(NumberFormatException nfe){
  //Log error here.
}

answered Mar 07 '14 at 21:27

user2793390

741
7
29

score 0 · Answer 4 · answered Mar 07 '14 at 21:29

You will want to use a Map in order to take the product type as an input and retrieve an integer output that is the cost of the type of product.

Map<String, Integer> products = new HashMap<String, Integer>();
products.put("shoes", 50);

and retrieve the value using

products.get("shoes");

You can find more on HashMaps here.

How can you multiply a string with an integer in Java?

4 Answers4