How to assign a total to a name in Java

I am using a switch statement to choose 5 products. I want to assign the total to a name I can add up

double total;
(prod1 * 12.80) = total1

problem is it says "total" is not initalized

I got prod1 * 12.80 to work, but I need the total of that computation to add to a statement like

System.out.println("grand total = " +  total1 + total2 + " = " ; 

All,

Here is the first part of my code switch. I have 4 more cases to the switch that all have totals. I need all thes开发者_运维知识库e totals from each switch to be added up for a grand total.

public class test 
{ 
public static void main(String args[]) 
{ 
//declare a scanner for user Input 
Scanner userInput = new Scanner(System.in); 
int choice; 
double prod1,prod2,prod3,prod4,prod5; 
double lineCost1 = 2.98;
double lineCost2 = 4.50;
double total1 = prod1 * lineCost1; // This is a intial set valueforthe   Grand total   but can't get it to work 

 
do 
{ 
//display our menu 
System.out.println("***ProductSelection***\n"); 
System.out.println("Please Select a Product Number from 1-5\n"); 
System.out.println("To quit the Program Please enter 6."); 
System.out.println("*********************"); 
System.out.println("Please enter your choice:"); 

//get user input 
choice = userInput.nextInt(); 

//switch the choice from user 
  switch(choice) 

 { 

 case 1://Product 1 
 System.out.println("Product 1"); 
 System.out.println("Please enter the Quantity you want:"); 
 prod1 = userInput.nextInt(); 
 System.out.println("Quantity = " +  prod1 + " at a Line Cost of " +"$"+ 2.98 + " = " +"$"+ (total1)); 
 break; 

THIS is THE ERROR I GET : variable prod1 might not have been initialized double total1 = prod1 * lineCost1; // This is a intial set valueforthe Grand total but can't get it to work ^ 1 error

What is wrong with the following? Why do you want to write your expression backwards?

double total = prod1 * 12.8;