java - 添加/保存的数据无效 (addPerson)

Question

Scanner sc = new Scanner(System.in);
Boolean valid =  true;
do{
    valid = true;
    //get first name input and valid
    System.out.print("Enter your First Name > ");
    String firstName = sc.nextLine();
    if(firstName.trim().length() > 25){
        valid = false;
    }
    //get last name input and valid
    System.out.print("Enter your Last Name > ");
    String lastName = sc.nextLine();
    if(lastName.trim().length() > 25){
        valid = false;
    }
    //get email input and valid
    System.out.print("Enter your Email > ");
    String email = sc.nextLine();
    if(email.trim().length() > 40){
        valid = false;
    }
      ctrl.addPerson(email, firstName, lastName);

}while(valid == false);

不断提示用户输入无效，但仍添加/保存无效数据 (addPerson)。我可以理解为什么要保存 invalid，但是我应该如何正确使用 if 呢？谢谢您的帮助!

<小时/>

我已经阅读了大家的建议和推荐，下面是编辑后的代码。希望能做得更好。

Scanner sc = new Scanner(System.in);
boolean valid =  true;
String firstName = null;
String lastName = null;
String email = null;
Date birthday = null;

        do{
            System.out.print("Enter your First Name > ");
            firstName = sc.nextLine();
        }while(firstName.trim().length() > 25);

        do{     
            System.out.print("Enter your Last Name > ");
            lastName = sc.nextLine();
        }while(lastName.trim().length() > 25);

        do{     
            System.out.print("Enter your Email > ");
            email = sc.nextLine();
        }while(email.trim().length() > 40);

        ctrl.addPerson(email, firstName, lastName);

Answer 1

您需要将方法addPerson置于类似的条件下

if(valid) {
    ctrl.addPerson(email, firstName, lastName);
}

我还建议您使用原始类型(boolean 而不是 Boolean)，没有理由在这里使用它的对象表示。