有一个问题与while循环重复

Question

我遇到问题，在用户回答是之后重复循环，这应该重复该程序，但它跳过正文并立即再次询问最后一个问题。

这是程序的一部分（当它要求怪物类时输入两栖动物）：

public class MH4 {

    public static void main(String[] args) {

        String answer = "yes";
        String monster, amphibian;
        String s2 = "Water", s3 = "Thunder";
        String b1 = "Head", b2 = "Front legs", b4 = "Hind legs";
        String f3 = "Fatigue", i1 = "Ice Blight", i2 = "Severe Ice Blight";



        Scanner keyboard = new Scanner(System.in);  

        while (answer.equalsIgnoreCase("yes")) {

            System.out.println("Which monster class do you want to look up?");

            monster = keyboard.nextLine();

            if (monster.equalsIgnoreCase("Amphibian")){

                System.out.println("\nThese are the monsters under that classification:\n");

                System.out.println("Tetsucabra\nBerserk Tetsucabra\nZamite\nZamtrios\nTigerstripe Zamtiros");

                System.out.println("\nWhich of these monsters would you like to gather information on?");

                amphibian = keyboard.nextLine();

                if (amphibian.equalsIgnoreCase("Tetsucabra"))

                    System.out.println("\nThis monster is weakest to: " + s2 + " and " + s3);

                System.out.println("\nThis monster's weakest point is its: " + b1 + ", " + b2 + ", and " + b4);

                System.out.println("\nThis monster can cause:\n" + f3 + "\n" + i1 + " *\n" + i2 + " *\n");                          

                System.out.println("* Tetsucabra only inflicts these while in the frozen seaway");

                System.out.println("\nImportant Notes:\n- Its tail becomes its weakest point while it is holding boulders.\n- The projectiles that it shoots drain stamina.");
            }

            else { 
                System.out.println("That monster class does not exist in this game.");
            }

            System.out.println("\nIs there another monster or monster class you wish to look up?");

            answer = keyboard.next();
        }
    }
}

如果你能弄清楚错误，请告诉我，因为我不知道它可能是什么。