You can't define method in another method. Change your code to this:
public class Interface {
private void run()
{
Scanner console = new Scanner(System.in);
Store store1 = new Store(); // MUST DO THIS
int demandRate, option, end;
double setupCost, unitCost, inventoryCost;
double sellingPrice, optimalOrder;
String name;
do {
System.out.println("Enter product data (0), Show product data (1), Show product strategy (2), Exit program (9).");
option = console.nextInt();
switch(option)
{
case 0: enterData();
break;
case 1:
break;
case 2:
break;
case 9: System.out.println("You chose to exit the program.");
break;
default: System.out.println("Please choose a valid option.");
}
} while (option != 9);
}
private static void enterData()
{
int demandRate, option, end;
double setupCost, unitCost, inventoryCost;
double sellingPrice, optimalOrder;
Scanner console = new Scanner(System.in);
System.out.println("Product name between 3 & 10 characters long: ");
String name = console.nextLine();
while ((name.length() < 3) || (name.length() > 10)) {
System.out.println("Please put in a name between 3 & 10 characters long.");
name = console.nextLine();
}
name = name.toLowerCase();
System.out.println("Demand rate: ");
demandRate = console.nextInt();
while (demandRate <= 0) {
System.out.println("Please put in a positive integer.");
demandRate = console.nextInt();
}
System.out.println("Setup cost: ");
setupCost = console.nextDouble();
while (setupCost <= 0) {
System.out.println("Please put in a positive number.");
setupCost = console.nextInt();
}
System.out.println("Unit cost: ");
unitCost = console.nextDouble();
while (unitCost <= 0) {
System.out.println("Please put in a positive number.");
unitCost = console.nextInt();
}
System.out.println("Inventory cost: ");
inventoryCost = console.nextDouble();
while (inventoryCost <= 0) {
System.out.println("Please put in a positive number.");
inventoryCost = console.nextInt();
}
System.out.println("Selling price: ");
sellingPrice = console.nextDouble();
while (sellingPrice <= 0) {
System.out.println("Please put in a positive integer.");
sellingPrice = console.nextInt();
}
}
public static void main(String[] args) {
Interface intFace = new Interface();
intFace.run();
}
}