Java IDE先打印两行，然后才能解析用户'；s输入

所以我现在很难解决这个问题。简而言之，我正在尝试为一个类创建一个银行应用程序。我正在写一个方法来打印并获取用户的输入，但是打印行在我获取输入之前会打印出这两行。这是我的实现

boolean done = false; 
        while(!done) {
            System.out.println("Welcome to Running Bank"
                        + "\nWhat would you like to do?"
                        + "\n1-Create Account"
                        + "\n2-Log-In"
                        + "\n3-Exit");
            choice = scanner.nextInt();
            switch(choice) {
            case 1:
                System.out.println("Input your username(No more than 15 characters: ");
                Username = scanner.nextLine();
                System.out.println("Input your password(Must be at least 8 characters and not over 24): ");
                Password = scanner.nextLine();
        }
    }
}

我期望它能做的是打印出“输入你的用户名”，然后在我得到用户的输入后再打印下一行。然而，现在发生的事情是，在我输入任何内容之前，两行都被打印出来了。 提前谢谢你

boolean done = false; 
        while(!done) {
            System.out.println("Welcome to Running Bank"
                        + "\nWhat would you like to do?"
                        + "\n1-Create Account"
                        + "\n2-Log-In"
                        + "\n3-Exit");
            choice = scanner.nextInt();
            scanner.nextLine();
            switch(choice) {
            case 1:
                System.out.println("Input your username(No more than 15 characters: ");
                Username = scanner.nextLine();
                System.out.println("Input your password(Must be at least 8 characters and not over 24): ");
                Password = scanner.nextLine();
        }
    }
}

现在应该可以了。在输入

choice

之后，我添加了一个

scanner.nextLine（）

，

choice=scanner.nextLine（）

（正如Johannes Kuhn在上面的评论中所说的那样）可能重复的Put

scanner.nextLine（）