请帮忙，在while循环中遇到问题

Question

我试图要求用户输入是或否，如果它是是，那么它将重新启动，并且将添加特征，因为他们进行了2次选择。但是，它不让我问Y / N，我显然在某个地方搞砸了。如果可能的话，我怎么能最小化代码，而不是使用那个令人眼花缭乱的优化if语句。

public static void main(String[]args)
    {
        //Number 1
        Scanner scan = new Scanner(System.in);
        int num = 0;
        int num2 = 0;
        int num3 = 0;
        int count = 2;
        String yesno;
        do
        {
            System.out.println("Which aircraft would you like to simulate?");
            System.out.println("1. Blimp");
            System.out.println("2. Helicopter");
            System.out.println("3. Fighter Jet");
            System.out.println("4. Space Shuttle");
            num = scan.nextInt();
            if(num<1 || num>4) {System.out.println("Invalid");}

        } 
        while(num<1 || num>4);
        do
        {

            System.out.println("What characteristics would you like? (Input one, then the other)");
            System.out.println("1. Position Trim ");
            System.out.println("2. Force Breakout");
            System.out.println("3. Force Gradient");
            System.out.println("4. Force Friction");
            System.out.println("5. Damping");
            System.out.println("6. Hard Stop");
            num2 = scan.nextInt();
            num3 = scan.nextInt();

            if(num2 == 1 || num3 == 1)
            {
                System.out.println("The position to which a flight control returns");
            }
            if(num2 == 2 ||num3 == 2)
            {
                System.out.println("A force that returns a control to Trim. This is a constant force applied toward Trim which remains the same despite how far the control is moved (displacement) and how fast a control is moved (velocity).");
            }
            if(num2 == 3 || num3 == 3)
            {
                System.out.println("A force that returns a control to Trim, but one that varies with displacement. The farther the control is moved, the stronger the force applied toward trim.");
            }
            if (num2 == 4 || num3 == 4)
            {
                System.out.println("A constant force that is opposite to the direction of movement");
            }
            if(num2 == 5 || num3 == 5)
            {
                System.out.println("A force that is oppisite to the direction of movement. Damping varies with velocity. The faster a control is moved the stronger the force.");
            }
            if (num2 == 6 || num3 == 6)
            {
                System.out.println("A force that simulates a mechanical limit of travel. By varying the Hard Stops, the range of travel can be adjusted");
            }
            if(num2 < 1 || num2 > 6)
            {
                System.out.println("Invalid input");

            }

            if (yesno.equalsIgnoreCase("y")) {
                do
                {

                    System.out.println("What characteristics would you like? (Input one, then the other)");
                    System.out.println("1. Position Trim ");
                    System.out.println("2. Force Breakout");
                    System.out.println("3. Force Gradient");
                    System.out.println("4. Force Friction");
                    System.out.println("5. Damping");
                    System.out.println("6. Hard Stop");
                    num2 = scan.nextInt();
                    num3 = scan.nextInt();

                    if(num2 == 1 || num3 == 1)
                    {
                        System.out.println("The position to which a flight control returns");
                    }
                    if(num2 == 2 ||num3 == 2)
                    {
                        System.out.println("A force that returns a control to Trim. This is a constant force applied toward Trim which remains the same despite how far the control is moved (displacement) and how fast a control is moved (velocity).");
                    }
                    if(num2 == 3 || num3 == 3)
                    {
                        System.out.println("A force that returns a control to Trim, but one that varies with displacement. The farther the control is moved, the stronger the force applied toward trim.");
                    }
                    if (num2 == 4 || num3 == 4)
                    {
                        System.out.println("A constant force that is opposite to the direction of movement");
                    }
                    if(num2 == 5 || num3 == 5)
                    {
                        System.out.println("A force that is oppisite to the direction of movement. Damping varies with velocity. The faster a control is moved the stronger the force.");
                    }
                    if (num2 == 6 || num3 == 6)
                    {
                        System.out.println("A force that simulates a mechanical limit of travel. By varying the Hard Stops, the range of travel can be adjusted");
                    }
                    if(num2 < 1 || num2 > 6)
                    {
                        System.out.println("Invalid input");

                    }
                    System.out.println("Would you like to re-select?(Y/N)");
                    yesno = scan.nextLine();
                    count += 2;
                }
                while(num2 < 1 || num2 > 6 || num3 < 1 ||num3 > 6 );

            }
            else if (yesno.equalsIgnoreCase("n"))
            {
                System.out.println("You've used " + count + " characteristics");
            }

        }
        while(num2 < 1 || num2 > 6 || num3 < 1 ||num3 > 6 );

    }
}

Answer 1

您的代码可以进行一些压缩，但主要问题是yesno变量从未初始化，因此条件if（yesno.equalsIgnoreCase（“y”））的计算结果为false，而下面的块从未计算，因此行

    System.out.println("Would you like to re-select?(Y/N)");
    yesno = scan.nextLine();

将永远不会被评估并且用户永远不会被询问。如果代码保持原样，则应在创建代码时设置yesno=“y”。但是，正如我所说，您的代码可以简化。