我正在尝试创建一个模拟驾驶汽车的程序。在我的程序中，我有以下循环，允许用户“驾驶”任意英里：

public void run() {
    do {
        System.out.println("How many miles would you like to drive?");
        int userInput = scanner.nextInt();
        if (userInput > 360) {
            System.out.println("You don't have enough fuel to drive that far! Please try again.");
            run();
        }
        System.out.println("You are driving: " + userInput + " miles.");
        try {   
            for(int c = 0; c < parts.size(); c++){
                parts.get(c).function(userInput);
            }
        } catch (BreakdownException e) {        
        }
    }while (getBoolean("Keep driving?"));

我想获取userinput变量并保存它，这样我就可以跟踪油箱中有多少英里。这是我目前的代码：

public void function(int milesDriven) throws BreakdownException {

    int mpg = 30;
    int gallons = 12;
    int totalMiles = gallons * mpg;
    int milesLeft = totalMiles - milesDriven;

    if(milesLeft <= 0) {
        throw new BreakdownException("You ran out of fuel!");
    }
    else if (milesLeft <= (totalMiles / 4)) {
        if(getBoolean("You are low on fuel! Refuel?")) {
            milesLeft = gallons * mpg;
            System.out.println("You now have enough fuel to travel " + totalMiles + " miles.");
        }
    }
    else {
        System.out.println("You now have enough fuel to travel " + milesLeft + " miles.");
    }

}

当前，每次第一个代码块中的循环运行时，第二个代码块中的milesdriven值都会重置。因此，每当用户“开车”时，他们的油箱就会自动加油。有没有一种方法可以存储userinput值以便它在循环之间保持不变？
谢谢！