[英]Is there any better way to create an object?
我正在从Student类创建一个新对象,但是,Student类包含一个来自Address类的对象,而Address类包含一个来自PostCode类的对象。 我尝试创建3个不同的对象,还有什么更好的方法吗?
public class Main{
public static void main(String[] args) {
PostCode p1 = new PostCode("Keiraville", "Wollongong", "NSW");
Address a1 = new Address (17, "Dalas",p1 , "Australia");
Student s1 = new Student("Huang", 314531, a1, "Csit121");
s1.print();
班级学生
public class Student {
String name;
int studentID;
Address address;
String courseID;
public Student(String name, int studentID, Address address, String courseID)
{
this.name = name;
this.studentID = studentID;
this.address = address;
this.courseID = courseID;
}
班级地址
public class Address {
int streetNumber;
String streetName;
PostCode postCode;
String country;
public Address(int streetNum, String name, PostCode postCode, String country)
{
this.streetNumber = streetNum;
this.streetName = name;
this.postCode = postCode;
this.country = country;
}
邮编类
public class PostCode{
String suburb;
String city;
String state;
public PostCode (String suburb, String city, String state)
{
this.suburb = suburb;
this.city = city;
this.state = state;
}
我也尝试过
Student s1 = new Student("Huang", 314531, Address(17, "Dalas", PostCode("Keiraville", "Wollongong", "NSW") , "Australia"), "Csit121");
两者似乎都是创建新对象的完全有效的方法。 在第二个版本中,您忘记了Address和PostCode之前的new
关键字。 否则,在有效性方面确实没有任何区别。 您可能会发现,在第二种实现中,您可能要超过80个字符。 惯例是使行短,通常少于80个字符。
为了打印对象的值,按照您的建议实现打印功能是一个有效的选择,但是在Java中,约定是在每个以字符串形式返回值的类中实现toString()
方法。 例如,在您的PostCode类中,其外观应类似于
public String toString() {
return " Suburb = " + this.suburb + " City = " + this.city + " State = " this.state;
}
然后,您可以通过
PostCode postCodeObject = new PostCode("Bla", "Bla2", "Bla3");
System.out.println(postCodeObject.toString());
如果您的值不是String类型,例如,它们可以是int类型,例如Studentid,则可以说类似
return Integer.toString(studentid);
只需使用多级继承的概念...在类的2中使用super方法nd将参数传递给super ...这样,您只需使一个对象nd将所有参数传递给该类的构造函数
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