在Java變量被陳述但被遺忘？

Question

我有這個Java代碼。這是一個簡單的小東西，我試圖通過除以已佔用房間的總數除以房間總數來獲得酒店的入住率。然而，當我嘗試編譯我得到的代碼時：

C:\Users\Jerome\Documents\Computer Concepts and Programming\Lab04\JRGlab04Num07\JRGlab04Num07.java:62: error: variable totalORooms might not have been initialized 
      totalORooms += numORooms; 
      ^
C:\Users\Jerome\Documents\Computer Concepts and Programming\Lab04\JRGlab04Num07\JRGlab04Num07.java:63: error: variable totalRooms might not have been initialized 
      totalRooms += numRooms; 
      ^
C:\Users\Jerome\Documents\Computer Concepts and Programming\Lab04\JRGlab04Num07\JRGlab04Num07.java:68: error: variable totalORooms might not have been initialized 
     ORate = totalORooms/totalRooms; 
       ^
C:\Users\Jerome\Documents\Computer Concepts and Programming\Lab04\JRGlab04Num07\JRGlab04Num07.java:68: error: variable totalRooms might not have been initialized 
     ORate = totalORooms/totalRooms; 
          ^
4 errors 

Tool completed with exit code 1 

所以爲什麼它會忘記我已經說過的變量。

import java.util.Scanner; //Needed for Inputting 
import java.text.DecimalFormat;//Needed for Rounding 

/** 
The pourpose of this lab is: 
To calculate the occupancy rate of a hotel 
by JEROME GERO Lab 04 Number 07 
*/ 

public class JRGlab04Num07 
{//Begin Class 
    public static void main(String[] args) 
    {//Begin Main Method 

     //Variables and introduction 
     double totalFloors, floor, numRooms, numORooms; 
     double totalRooms; 
     double totalORooms; 
     double ORate; 
     System.out.println("Welcome to the Hotel Occupancy Calculator.\nPlease enter the number of floors we will be dealing with:"); 
     Scanner keyboard = new Scanner(System.in); 
     DecimalFormat formatter = new DecimalFormat("#0.00"); 


     totalFloors = keyboard.nextInt(); 
     floor = 0; 

     while(totalFloors < 1) 
     { 
      System.out.println("No, lets try that again."); 
      totalFloors = keyboard.nextInt(); 
     } 

     System.out.println("Okay"); 


     while(totalFloors > 0) 
     { 

      ++floor; 
      System.out.println("Now enter the number of rooms on floor " + floor); 
      numRooms = keyboard.nextDouble(); 


      while(numRooms < 10){ 
       System.out.println("The Number of rooms nust be greater than 10.\nPlease enter the number of rooms."); 
       numRooms = keyboard.nextDouble(); 
      } 


      System.out.println("Now enter the number of occupied rooms on that floor:"); 
      numORooms = keyboard.nextDouble(); 


      while(numORooms > numRooms){ 
       System.out.println("No, the Number of Occupied rooms can not be more than the number of rooms on this floor.\n" + 
       "Please enter that again."); 
       numORooms = keyboard.nextDouble(); 
      } 


      totalORooms += numORooms; 
      totalRooms += numRooms; 
      --totalFloors; 

     } 

     ORate = totalORooms/totalRooms; 

     System.out.println(ORate); 

    }//End Main Method 
}//End Class 

Answer 1

您不爲totalRooms指定一個值。該錯誤告訴你它還沒有被初始化。

double totalRooms = 0.0;