Question

我正在玩Java类和继承，但是我不了解构造函数的一部分。在我的父类中，我hard-coded bankAccountStatus达到以下值Bank Account is Low。然后，我创建了一个名为MemberStatus的子类，并将构造函数参数定义为与父类相同的输入。但是，如果我在调用bankAccountStatus时尝试将new MemberStatus更改为其他名称，则不会。我当然可以将其更改为参数名称，以使其正常工作，但是我试图理解其功能。是否有必要更改该值而无需在父类中将其转换为this.bankAccountStatus = bankAccountStatus;

class User {
  constructor(firstName, lastName, phone, bankAccountStatus){
    this.firstName = firstName;
    this.lastName = lastName;
    this.phone = phone;
    this.bankAccountStatus = 'Bank Account is Low';
  }
}

class MemberStatus extends User {
  constructor(firstName, lastName, phone, bankAccountStatus, vipStatus){
    super(firstName, lastName, phone, bankAccountStatus);
    this.vipStatus = vipStatus;
  }
}

let john = new MemberStatus('John', 'Doe', '555-123-4567', 'Bank Account is Wealthy', 'Gold');
console.log(john);

Answer 1

如果要默认将其添加到User的构造函数中，为什么要麻烦呢？扩展类的构造函数不必相同：

class User {
  constructor(firstName, lastName, phone){
    this.firstName = firstName;
    this.lastName = lastName;
    this.phone = phone;
    this.bankAccountStatus = 'Bank Account is Low';
  }
}

class MemberStatus extends User {
  constructor(firstName, lastName, phone, bankAccountStatus, vipStatus){
    super(firstName, lastName, phone);
    this.bankAccountStatus = bankAccountStatus
    this.vipStatus = vipStatus;
  }
}

let john = new MemberStatus('John', 'Doe', '555-123-4567', 'Bank Account is Wealthy', 'Gold');
console.log(john);

Answer 2

您问：

无论如何都可以更改该值，而无需在父类中将其转换为this.bankAccountStatus = bankAccountStatus

如果您看一下构造函数：

class User {
  constructor(firstName, lastName, phone, bankAccountStatus){
    this.firstName = firstName;
    this.lastName = lastName;
    this.phone = phone;
    this.bankAccountStatus = 'Bank Account is Low';
  }
}

class MemberStatus extends User {
  constructor(firstName, lastName, phone, bankAccountStatus, vipStatus){
    super(firstName, lastName, phone, bankAccountStatus);
    this.vipStatus = vipStatus;
  }
}

您正在传递字符串作为您的第四个用户变量参数，但是您从未访问过它。如果您想为this.bankAccountStatus提供默认值，可以将其放在参数中，如下所示：

class User {
  constructor(firstName, lastName, phone, bankAccountStatus = 'Bank Account is Low'){
    this.firstName = firstName;
    this.lastName = lastName;
    this.phone = phone;
    this.bankAccountStatus = bankAccountStatus;
  }
}

祝您的项目好运！

硬编码Javascript构造函数参数是否可以？

2 个答案: