在構造函數中聲明方法

Question

當我在構造函數中聲明方法時，出現錯誤「; expected」。不知道爲什麼。你能幫我理解嗎？

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); 
    } 

我得到錯誤的行，我宣佈long nightsStay（）;

Answer 1

你不能這樣做

long nightsStay(); 

如果你定義你需要一個名字，然後你可以將價值指向它的變量，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()返回的東西，那麼你必須從void改變返回類型爲你喜歡的返回類型，這是你的情況long。