如果while循环内的分支未按预期执行

如何解决如果while循环内的分支未按预期执行

这是我正在使用的代码。此处引用的其他类已经过测试和运行，尽管它们不会影响此处的语句功能。

import java.util.Scanner;

public class TransferTest 
{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);

        double transferAmount;
        Account acct1 = new Account(100,null);
        Account acct2 = new Account(100,null);


        System.out.print("Choose an option: "
                + "\n1 <Enter>: to transfer from account 1 to account 2"
                + "\n2 <Enter>: to transfer from account 2 to account 1"
                + "\n3 <Enter>: to quit");
        int userOption = scan.nextInt();
        scan.nextLine();

        while(userOption != 3); 
        {
            if (userOption == 1)
            {
                System.out.print("You chose transfer from account 1 to account 2"
                        + "\nEnter an amount to transfer: ");
                transferAmount = scan.nextInt();
                acct1.transfer(acct2,transferAmount);
            }
            else if (userOption == 2)
            {
                System.out.print("You chose transfer from account 1 to account 2"
                        + "\nEnter an amount to transfer: ");
                transferAmount = scan.nextInt();
                acct2.transfer(acct1,transferAmount);
            }
            else if (userOption == 3)
            {
                System.out.println(acct1.toString());
                System.out.println(acct2.toString());
            }
            else
            {
                System.out.println("Invalid input");
            }

            System.out.print("Choose an option: "
                    + "\n1 <Enter> to transfer from account 1 to account 2?"
                    + "\n2 <Enter> to transfer from account 2 to account 1"
                    + "\n3 <Enter> to quit");
            userOption = scan.nextInt();
            scan.nextLine();
        }

        System.out.println(acct1.toString());
        System.out.println(acct2.toString());
        scan.close();
    }

}

我要这样做是提示用户选择由数字值表示的三个选项之一。然后跟随该值的if分支，在用户为1或2的情况下询问用户一个金额。直到用户选择选项3为止，不退出while循环。实际上是，当输入3或超出指定范围的值时，该程序正常工作，但是当1或2个被选择作为选项没有任何反应，甚至没有报表打印输出。非常感谢您提供帮助，以使其正常工作。

解决方法

while循环后使用分号。

while(userOption != 3);

实际上等于：

while(userOption != 3) {
  // do nothing
}

因此该行之后没有代码被执行。