Jlist计算

Question

i'm trying to calculate the total amount from the text file, so far I have printed the prices out but i'm not sure what to code to use to calculate the total amount.

OrderPage.setText("Diner Number | Food | Quantity | Calories | Price");
       DefaultListModel listModel = new DefaultListModel();
                    try {
                        FileReader file = new FileReader("savedFoodData.txt"); 
                        BufferedReader buffer = new BufferedReader(file); 

                        while ((line = buffer.readLine()) != null) { 
                                outputDinerChoice = line;
                                outputDinerChoice = outputDinerChoice.replaceAll(",", "     ");                     
                                listModel.addElement(outputDinerChoice);    
                                dinersChoice = outputDinerChoice.split("     ");
                                System.out.println(dinersChoice[4]);
                            }

the file ("savedFoodData.txt") would set out like this:

"Diner Number | Food | Quantity | Calories | Price" 

Which would contain:

1/2,Burger,1,156kcal,£2.70
1/2,Chicken,1,159kcal,£3.90
1/2,Steak,1,50kcal,£7.00
2/2,Noodles,1,398kcal,£4.90
2/2,Pizza,1,156kcal,£2.70
1/2,Beer,1,20kcal,£4.10
1/2,Coke Tea,1,5kcal,£1.50

And this code would print out

System.out.println(dinersChoice[4]);
£2.70
£3.90
£7.00
£4.90
£2.70
£4.10
£1.50

And I'm trying to calculate the total price from this, how would I do this?

Answer 1

• Split the line into array of columns
• Use substring to convert "£2.70" => "2.70"
• Convert the "2.70" to a number using Double.parseDouble()

Example

String line = "1/2,Burger,1,156kcal,£2.70";
String[] columns = line.split(",");
double value = Double.parseDouble(columns[4].substring(1));

Integrated

double sum = 0;
while ((line = buffer.readLine()) != null) {
    String[] columns = lines.split(",");
    sum = sum + Double.parseDouble(columns[4].substring(1));
}