java: How do I use printf to print a dollar sign and a double with 2 decimals?

Question

I'm really bad with printf. How do I add %$.2f to my String format so that I can get something clean like this: (I forgot to add '$' earlier)

MP3 Player cost:                        $580.39
Smart Phone cost:                       $510.93
Digital Watch cost:                     $495.99
Tablet cost:                            $643.17
Portable Gaming System cost:            $485.17



import java.util.Scanner;

public class test2 {

    public static void main(String[] arg) {

        Scanner in = new Scanner(System.in);

        int [][] matrix = { // 5 rows, 7 cols
                { 9, 13, 4, 7, 1, 14, 10},
                { 8, 2, 12, 11, 6, 15, 2},
                { 9, 6, 7, 10, 15, 8, 3},
                { 12, 14, 8, 15 ,2 , 7, 8},
                { 12, 10, 3, 11, 8, 3, 5},
        };

        String [] product = new String [5];
        product [0] = "MP3 Player";
        product [1] = "Smart Phone";
        product [2] = "Digital Watch";
        product [3] = "Tablet";
        product [4] ="Portable Gaming System";

        double [] price = {10.75, 15.27, 5.98, 9.67, 4.32, 12.50, 1.42}; // 7 elements

        costOfEach(matrix, product, price);
    }

    // compute and display the cost of manufacturing each device
    public static double costOfEach(int matrix[][], String[] product, double price [] ){
        double cost = 0.00;
        String item = "";
        double maxCost = 0.00;
        double minCost = Double.MAX_VALUE;
        int maxCostIndex = 0;
        int minCostIndex = 0;

This right here. I have tried many combinations but no result

        String format = "%-40s%s%n"; 
        for (int row = 0; row < matrix.length; row++){
             cost = 0;
             for (int col = 0, i = 0; col < matrix[0].length && i < price.length; col++, i++){

                 cost += matrix[row][col] * price [i]; 
             }

             System.out.printf(format, product[row] + " cost: $%.2f", cost);
        }
                return cost;
    }

}

Answer 1

The answer above is correct, to add $ sign just edit following line:

String format = "%-40s$%.2f%n";

Your output:

MP3 Player cost:                        $580,39
Smart Phone cost:                       $510,93
Digital Watch cost:                     $495,99
Tablet cost:                            $643,17
Portable Gaming System cost:            $485,17

Answer 2

I have made some changes. According to your requirement your code should be like this:

import java.util.Scanner;

public class test2 {

public static void main(String[] arg) {

    Scanner in = new Scanner(System.in);

    int [][] matrix = { // 5 rows, 7 cols
            { 9, 13, 4, 7, 1, 14, 10},
            { 8, 2, 12, 11, 6, 15, 2},
            { 9, 6, 7, 10, 15, 8, 3},
            { 12, 14, 8, 15 ,2 , 7, 8},
            { 12, 10, 3, 11, 8, 3, 5},
    };

    String [] product = new String [5];
    product [0] = "MP3 Player";
    product [1] = "Smart Phone";
    product [2] = "Digital Watch";
    product [3] = "Tablet";
    product [4] ="Portable Gaming System";

    double [] price = {10.75, 15.27, 5.98, 9.67, 4.32, 12.50, 1.42}; // 7 elements

    costOfEach(matrix, product, price);
}

// compute and display the cost of manufacturing each device
public static double costOfEach(int matrix[][], String[] product, double price [] ){
    double cost = 0.00;
    String item = "";
    double maxCost = 0.00;
    double minCost = Double.MAX_VALUE;
    int maxCostIndex = 0;
    int minCostIndex = 0;

    String format = "%-40s$%.2f%n";
    for (int row = 0; row < matrix.length; row++){
         cost = 0;
         for (int col = 0, i = 0; col < matrix[0].length && i < price.length; col++, i++){

             cost += matrix[row][col] * price [i]; 
         }

         System.out.printf(format, product[row] + " cost:", cost);
    }
            return cost;
}

}

Answer 3

No, no, no! The problem is the currency symbol. If you hard code it, as shown in the answers above, you are giving up internationalization. While C# has a "C" placeholder for currency and thus displays the correct currency symbol such as $, ¥, or € printf in Java does not and forces you to hardcode the currency symbol. Solution is to create NumberFormat objects and this effectively nullifies the advantage of printf over print/println.