Question

Person.java

public class Person {
    public String firstname;
    public String lastname;
    public Date dob;
    public boolean sex;

    public Person(String firstname, String lastname, Date dob, boolean sex){
        this.firstname = firstname;
        this.lastname = lastname;
        this.dob = dob;
        this.sex = sex;
    }

    public Person(String firstname, String lastname, Date dob, String s){
        this.firstname = firstname;
        this.lastname = lastname;
        this.dob = dob;
        if (s.charAt(0)=='f' || s.charAt(0)=='F') sex = true; else sex = false;
    }

Date.java

public class Date {
    public int day;
    public int month;
    public int year;

    public Date(int day, int month, int year)
    {
        this.day = day;
        this.month = month;
        this.year = year;
    }
}

为什么这是错的？如何正确创建对象？这是一篇论文，所以上面的类不能改变。

public static void main(String[] args) {
    Person person1 = new Person("Adeline", "Wells", (12,4,1992), false);
}

Answer 1

问题是你的字段日期进入人类类也是一个类，所以你这样做：

public static void main(String[] args) {
     Date d = new Date(12,4,1992);
     Person person1 = new Person("Aaron", "Wells", d, false);
}

否则，如果你想直接过去一个月和一年，你可以这样做：\ / p>

public Person(String firstname, String lastname, int d, int m, int y, boolean sex){
        this.firstname = firstname;
        this.lastname = lastname;
        this.dob = new Date(d, m, y);
        this.sex = sex;
    }

现在你可以做到

public static void main(String[] args) {
    Person person1 = new Person("Adeline", "Wells", 12,4,1992, false);
}

Answer 2

您可以在以下一行中执行此操作：

public static void main(String[] args) {
    Person person1 = new Person("Aaron", "Wells", new Date(12,4,1992), false);
}

无法从自定义类创建对象

2 个答案: