在构造函数中声明方法

Question

当我在构造函数中声明方法时，出现错误“; expected”。不知道为什么。你能帮我理解吗？

public class Reservation { 
Date arrivalDate = new Date(); 
    Date departDate = new Date(); 
    Reservation(Date arrDate, Date deptDate) 
    { 
    arrivalDate = arrDate; 
    departDate = deptDate; 
    long nightsStay(); 
    } 
void nightsStay() 
    { 
     long days = (departDate.getTime()-arrivalDate.getTime())/(24*60*60*1000); 
    } 

我得到错误的行，我宣布long nightsStay（）;

Answer 1

你不能这样做

long nightsStay(); 

如果你定义你需要一个名字，然后你可以将价值指向它的变量，但你缺少的名字。

public class Reservation { 
    Date arrivalDate = new Date(); 
    Date departDate = new Date(); 
    long nightsStay; // add that line 

    Reservation(Date arrDate, Date deptDate) 
    { 
     arrivalDate = arrDate; 
     departDate = deptDate; 
     nightsStay = nightsStay(); // change that line 
    } 

    long nightsStay() 
    { 
     long days = (departDate.getTime()-arrivalDate.getTime())/(24*60*60*1000); 
    } 
} 

例子：

long l = 5; //variable l gets value 5; 
l = nightsStay(); // calling method nightsStay and storing the result in l; 
long nightsStay(); // is neither one 

如果你想方法nightsStay()返回的东西，那么你必须从void改变返回类型为你喜欢的返回类型，这是你的情况long。